Monitor Image Blurry After Cleaning: Resolution Adjustment & System Restore Failed

and maybe you rummaged in the monitor while "cleaning" the computer?

no, the monitor was just disconnected
currently, I "broke" the system, wanting to fix the resolution in various ways and I will have to do the formatting ... but it's only on Sunday because I will not have contact with my computer over the weekend.
after formatting I will write if the problem has disappeared or if I still need help.
thank you all for your commitment and help, if someone else had any ideas what could be caused by it, please write
I remind you: the computer was ok, I gently disassembled everything, carefully put everything back together and after turning on the computer, the screen resolution changed and I could not set it as before (1440x900)

Give screen properties - settings - advanced - tab 'tab' - list of all modes and look for your resolution there.

The format was there, the image was there
the system was rebooted and everything is back to normal, but I still have no idea what could have caused this failure
but thank you all for your help and commitment