Repairs don’t always work
As you might gather from the long list of repairs on this site. I am a big fan of repairing. A good repair can make your item better than the original and it can last for a long time.
However not all my repairs go well. I once tried to help my brother in law fix a phone. He’d bought a kit to replace a part but we managed to damage the phone taking it apart. That’s actually quite common when repairing and I often end up swapping out stripped screws or touching up paint following a repair. If a device is not designed for easy repair (and many phones are not) then making things worse is not uncommon. Though
Sometimes repairing just delays the inevitable such as the oven thermostat repair which then broke again
This weekend I tried to fix a mirror using a windscreen repair kit. I’d managed to put a crack in it whilst moving some large items around the room (it might have been a door or a bed head?). My thought was that the repair kit would bond the mirror together and possibly reduce the appearance of the crack.

However, what

Bad luck?
Breaking mirrors is always associated with 7 years back luck. I’d always thought that this was due to the use of silver-mercury amalgams in early glass mirrors. Hence breaking the mirror was something to be avoided so you’d not get mercury poisoning.
Other theories include the fact that mirrors were expensive so might take 7 years to save up for a replacement. Mirror makers could not make good quality glass so encouraged this superstition so that people would look after their mirrors and not blame them for defects.
Mirror History suggests that the source of this story was way back with the Romans and their seven year cycle of renewal. They believe that “If the persons looking into the mirror were not of good health, their image would break the mirror and the run of bad luck would continue for the period of seven years, at the end of which their life would be renewed”.
My own theory is that mirrors are made from a very delicate form of glass and that I’ll be finding small splinters of glass for many years to come.