HP Computer Lost Usable Ram?

Hello, I've had a HP Desktop for a few months with 6GB Of Ram, 5.95 or so usable.
Recently my computer has been going slow, so I check around and I only have 2GB of usable RAM, is it possible to get it back?
Sorry if I'm not giving helpful details, ask any questions if needed.

Hello PrinceTuna, and welcome to Seven Forums.

When you restart the computer, how much memory does it show you having in the boot screen or in BIOS?

Double check using the tutorial below to make sure that you have the Maximum memory box unchecked in the Boot tab of msconfig.

http://www.sevenforums.com/tutorials/66482-memory-set-maximum-amount-used-windows-7-a.html

Hope this helps for now,
Shawn

Yes, thank you so much.

Did that sort it?