Computer error/ bsod troubleshoot

3 weeks ago my computer first had errors occur i am on windows 7 btw. The window i was using started to lag and or glitch a bit so i closed it and went to re open firefox but no desktop icons or anything on the start / date and time bar were there. I couldt right click the desk top either. so i tried doing ctrl alt delete and a box popped up saying ctrl alt delete could not be accessed at this time or something. so i clicked the power button and a shutdown thing popped up saying are you sure you want to shut down so and so program is still running i clicked okay but it didnt shut down all the way the display went black but computer seemed still on. so i did a hard shutdown. when i rebooted the computer started normaly and all seemed fine. then 30 min later same thing happened exept when i restarted it said no boot device selected. i turned it off and restarted 5 min later it booted normally so then again after 20 5-40 minutes i forget i started getting glitchy a bit then it went to BSOD With a kernal inpage erorr is what it said then it automaticly restarted. it booted normally so i went to look for my minidump file which should have been created or a .dmp file no file existed so i check my setting and they were set right, to send small memory dump apon crash. so i figrued this ment that the error wasn't big enough for the computer to write a dump for. So then i did a chkdsk/r and a another scan i forget which but someone recomended it to me. again next time i tried to use my computer after a while the desktop icons disapeared so i did hard shut down and put in my windows 7 recovery disk and did the recomended checking errors on windows 7 and i think the memory checking option. that didnt solve the problem because it happened again later that day s so i did a system resore uninstalled my latest downloads before the error occured/ drivers. So 3 weeks later after not really using my computer too much and doing reasearch on my laptop on how to problem solve i keep getting bsods(i got diffrent bsod error then kernel inpage recently i forget which) with no minidumps the desktop disapearing and no boot divece errors(occasionally). At this point i think i need to wipe my hard drive and re-enstall windos 7 and see if that fixes the errors but i dont know how to do that really and have alot of important things like photoshop/ ableton projects that i cant lose, and i feel like if i back everything important up the files wont be the same due to me using this main drive along with another one with files on both to certain things. Any Advice on how to solve my problem would be great Thanks!