you can go into the boot menu (hit one of the F keys usually its F8 or F12 but could be any one of them before the windows icon comes up) and choose a time where you would like to restore your computer to... there should be several points saved already...
it keeps your operating software intact but wipes everything else
any software/work that is critical should be saved before this because you never know what your computer will mess up... but that should be done even if you dont want to a system restore (recovery)
this method is usually reserved for an infected pc/critical errors but i can also be used to get any junk you dont want anymore out and usually speeds up the computer
current antiviral software, weekly running of disk clean up, and a yearly running of your disk defragmenter keeps most problems at bay though... both of these are found in accessories/system tools...
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