I have some mounted towel racks in the bathroom on the wall and they're coming off... I'm curious how can i firmly get them back on the wall without a re-mount or glue.
Side note: This is rather more something that belongs on diy se than lifehacks. Sometimes there really is not good jury rigged substitute for doing a job properly using dedicated tools and products
In addition to Niels suggestion there are a variety of dedicated wall fixings, depending on the kind of wall you have. Some of these fixings work better than others on a tiled wall
Here's a pic of a selection:
If your wall is drywall, with tiles:
On the left is the one I'd recommend for a towel rail simply because the rail is pulled on often. The metal sleeve inserts into the wall and the bit in the middle that looks bent splays out to grip the back side of the drywall when the screw is wound tight.
If your wall is drywall without tiles:
The one that looks like a screw with wings is similar, after pushing though the hole the wings spring outwards and provide a firm grip on the back of the wall. This is a secure fixing and good for something that will be pulled on a lot. It is less suitable for tiles because of the siz and shape of hole that is needed to get the wings to fit through. You either make a fitted square hole (hard in a tile) or drill a large round hole that can admit the square profile of the folded wings- it's a lot larger than necessary as a result
The one that looks like a big worm gear/screw is for hanging things that won't be disturbed as often, the large threads grip the drywall and hold on well, providing a secure mounting for a smaller screw. Not suitable for tiles because the screw threads won't chew into the tile. Breaking the tile out to allow the screw threads to reach the drywall could be disastrous
Drywall with or without tiles, light duty use:
Then we see the one Niels is probably discussing, there the action of winding in the screw splays the plastic legs out
Non drywall (i.e. Solid, brick, stone, concrete etc) with or without tiles:
On the rightmost, is a plug typically used for solid walls; a hole the same diameter as the plug is used, and driving the screw in forces the plug apart and into the surrounding brick for enhanced grip. Don't use these on drywall; it just crushes the drywall and loosens the whole lot. Drywall fixings that are subject to a lot of force/movement should be the kind of fixing where the back of the drywall is gripped
If your wall is drywall:
You asked how you can reattach this towel rail without glueing or remounting (I presume you mean elsewhere) and the answer may be that you can't, if the structure of the wall is badly destroyed. If the damage is mild, remount with one of the two leftmost fixings. There isnt much of a life hack for this, and I recommend that you treat with caution any advice to pack the hole out with eg matchsticks or similar, and wind the screw in again.. such solutions don't grip the drywall in the right way and will eventually ruin the hole to an even larger mess, making repair harder
If the wall is non drywall:
Many times the problem is that the plaster later can be quite thick and the fixing has only been embedded in the plaster section. The plug crushes the plaster and works loose over time. A deeper hole should be drilled of the correct size, and an appropriate plug and longer screw used. Use multiple plugs or a stick to push the plug into the wall and ensure the screw is long enough to reach effectively. Mark your drill bit before you pull it out of the wall to know how deep the hole is. If wall dust is making it difficult to get the plug in, use a drinks straw to blow the dust out. Close your eyes
And for the final lifehacky part: if you have a solid wall then one or more wooden sticks, matches, cocktail sticks, chopsticks or even something you've shaved off another bit of wood using a knife is fine, as something to pack the hole with before you drive the screw in. Same principle as the plastic plug; the screw forces the wood outwards against the sides of the hole, gripping the block. Fatter screws work better
At the hardware store you can buy a variety of different little thingies which will allow you to remount a towel rack into a (sheetrock, a.k.a. "drywall") wall from which the original screws have been torn loose.
These are called drywall anchors or inserts and consist of a plastic cylinder which is pressed tightly into the torn-out hole. The mounting screw is then threaded into the center of the plastic insert, into which its threads readily engage, and the act of screwing the screw into the insert pushes the insert apart so that its outside is pressed into very tight engagement with the surrounding drywall.
These are available in different sizes to accomodate different screw diameters, and generally require you to drill out the torn hole slightly larger so the insert can be squeezed in. The helper person at the hardware store can show you what size insert to buy and what size hole it needs to be pressed into.
Inserts like this cost just a few pennies each and it takes just a minute or two to install them.
I have in the past removed the item from the wall and investigate why the it has become loose.
If the hole has become too large and this is why it has become loose, I would initially try and use a larger raw-plug that is still capable of holding the same size screw and reattach this to the wall.
If this is not possible I would use a raw-plug that is of the same size as before but also insert matchsticks between the wall and the raw-plug to fill the gap and allow the towel holder to be re-attached firmly - please bear in mind that I am talking about a solid wall and would only use this for items that would not need to hold a lot of weight, for instance a coat hook, towel rail or toilet roll holder. Anything that would require weight bearing or is in a position that could cause damage should be re-fixed by filling the holes and re-drilling new holes in a different position on the wall - I am also assuming that the holes are solid enough and the wall by the hole is not crumbling in any way
If the hole is not the problem then inspect the towel rail for any other damage and repair or replace as necessary.
If it is a plugs-and-screws fixture and the plugs are not tight enough you can take out the plugs and insert some matches along with the reinserted plug. That would be a quick fix.
If the holes haves become too wide and crumbly you can also make a bit of dry wall paste (or use filler from a tube), fill the holes with it and gently push in the old plugs. Let it set for a day or two and you should have some new tight and strong holes for your screws again.