Right, I'm shit with computers and am having a serious issue at the moment.

I've been away working for a few days so not used my computer. I've now come home, turned on laptop and logged in through the password bit for windows as normal. However, rather than my user account opening, it seems to have restored factory settings.
All programs are gone, all settings, every single file, song, picture, video that I've saved over the last few years is all gone.

It's like a new computer with nothing on it. However, if I click properties in the My Computer bit, it said first that it had 300mb of free space, which was impossible as I know there was a lot more space than that. Then I restarted it, same again except this time it said there was 3gb of free space.

Have I lost everything or has it somehow logged me into the wrong account?

I've been sat restarting it repeatedly in the hope it'll sart again properly, but I don't know. Any suggestions?

Someone help, cos I'm having a panic as I haven't backed anything up for at least 6 months and it's looking like I've lost the lot!