I formated my pc and now i dont have sound!!!

If you have the discs that came with the sound card/computer, run the installation program from that.

If not and you have internet access from that computer and it's a Windows OS, try this:
go to "System" under in "Control Panel."
Click the "Hardware" tab.
Click the "Device Manager" button.
Find the "Audio Devices" (or "sound"...can't remember...it has the megaphone picture next to it)
Expand the tree if it's not already expanded(click the plus sign next to it)
Right click the Icon under the "Audio Devices" with a yellow question mark and select properties. (there might be a selection to "install driver." if so, select that.
When it asks if you want it to search for drivers on the internet, select "yes, this time only"
It should find what you need.

If not you'll need to find out what company has the made your sound card and go to their website or google "(company's name) audio drivers."

If you don't have internet access on that computer, you can find a computer with internet access, find the driver (by going to the company website or googling), and save it to USB memory stick, or CD and copy it to your computer.