No sound on my computer

Hello,

When I restarted my laptop yesterday, I found that my audio was totally gone. Five minutes before it had been working perfectly. I checked device manager and got no error messages, rolled back the driver, reinstalled the driver. According to my computer, everything seems to be in working order, but nonetheless, my sound is still gone. I'm thinking that my sound card might be toast. I'm using a Toshiba Tecra M10-S3401 notebook with Realtek HD audio. XP Service Pack 3 is installed, everything is up to date...is there anything else I can do? Thanks in advance!