Need help: memory write/read failure

So I don't know exactly what I did but now when I turn on my computer I get the error below. Something similar has happened before but I was able to get to the boot or setup menu. Now I can't even do that, it won't even let me get there. I've tried reseating my memory, I even tried switching the memory but nothing has worked. Is there anything I can do? One note is that I had less than a gig of memory left when I last turned it off. If there's nothing I can do for the computer is there any way I can get all of my files out of it? Thanks...

Memory write/read failure at 40216E24, read 21CE61CE expecting 21CE21CE

To resolve this issue, try to reseat the memory.

Decreasing available memory

Memory address line failure at 40210000, read 21CE21CE expecting DEDEDEDE

To resolve this issue, try to reseat the memory.

Decreasing available memory

The amount of system memory has changed.

If you did not change your memory...

To resolve this issue, try to reseat the memory.