the power went out while i was working on computer, tried to reboot and power went out again. Computer is hooked up to surge protector. But sound has stopped working.........how to figure out this problem?

The crashes have possibly corrupted the driver(s) or associations, click on Start - Control Panel - System - Hardware - Device Manager, look for any signs of conflict (they will stand out if there are, if none expand the sound sections and in turn 1 at a time select to uninstall them (when asked to reboot say No, not until you do the last one), some may not have that option, thats fine leave it and move to the next, repeat until complete and reboot, allow the system to auto install them and hopefully everything should behave again.