I operate windows 7 64-bit and this morning my laptop (dell inspiron 1545) was absolutely fine, but now if i try to open any files I just keep on getting error messages. If i try opening documents or images I just get the same error messages "class not registered". Any music files I just get "no such interface supported" and that is the same with any video files. Also I cannot open many of my programs including all of microsoft office. In addition I can't uninstall programs or install new ones. I have tried running registry cleaners and running "sfc scannow" for example, deleteing tons of files that could be mildly dodgey and of course tried restarting my laptop numerous times, but not being a techie i have no idea what to do! please help and post any and all solutions you may have, but please post things step by step. Thank you in advance!
note: 6gb ram, 640gb HD, genuine windows 64bit, AVG 9.0, microsoft security essentials, everything should be pretty up to date!