Computers are a pain!

Last night I transferred a large file of freebie templates that I collected over the month from National Scrapbook Day and Facebook. I recently started playing around with templates after a CT I was on switched over to them so I spent the month collecting lots of them. Not all had the PNG files I needed but that was OK because I had lots of ideas to work with. My file just disappeared between last night and today. All I did before shutting down the computer was run a maintenance program and defragged aprox. 1,300 files. Today I signed on the computer and the whole file was missing off my EHD. I cannot locate them anywhere on my computer. Then if that wasn't bad enough I am having issues where my computer says files need passwords when they don't and I can only download part of a file. One designer actually had her work on MediaFire, 4Shared and the store system and the same file reads the error each and every time I've downloaded. I've cleared my cookies, the cache file and used three different browsers - Safari, IE and AOL all with the same results. How ever did we live life without these machines?!