Question, how did your "Friend" manage to reinstall your OS (I'm guessing VHP 32Bit here)?
One of the first thing I attempted when I received my Laptop, was to run the Backup Installer, which I met with less then stellar results. Thankfully I was able to request such Install Media under the Warranty Period. Which came with the standard VHP x86(32Bit) OS from Microsoft, Microsoft Works / Office 2007 STE, an Applications Disk and more importantly the Driver Disk.
Your lack of Sound, sounds like a classic Driver Problem to me. This should be fairly simple to find out though.
Start -> Control Panel -> (Switch to "Classic View"!!) -> Device Manager: To bring up the Device Manager Applet.
If you find a load of Yellow "!"s everywhere this is a surefire sign that you are in need of Drivers, Red "X"s could be an indication of poorly (or incorrectly installed Drivers.
In which case I could offer you this Link: http://support.ts.fujitsu.com/com/suppo ... loads.html
which should, help you to track down such Drivers that you might still have outstanding.
A proper Device Manager should be closed up without any "!"s or "X"s visible.
In such a case, where your Sound is still not ~working~, I would advise you check the Mute Button(s) (i.e. Hardware / Software).