You forgot to tell us what happens when you try to read this disc, and which version of Windows you are running (e.g., XP SP1 should be able to read most old packet-written discs natively). How do you know it's a UDF disc?
Well, if you aren't running XP SP1, you could try EasyWriteReader from Ahead's site (go to InCD's download page, select InCD | Utility). You don't need to worry, since it uninstalls cleanly. Anyway, if it doesn't help, don't forget to uninstall it via Add/Remove Programs before trying other readers.
Next, you may try Roxio's UDF Reader listed at the end of this page http://www.roxio.com/en/support/ecdc/software_updatesv4.jhtml
To make sure that you can get rid of it completely if it doesn't work, you may create a system restore point before installing it, or use some monitoring tool to detect what it installs in C:\Windows\System32 and C:\Windows\System32\Drivers (I guess UdfReadr_XP.sys and possibly Cdudf_XP.sys); this is for XP. As an additional precaution, you may search for LowerFilters in the registry and write down the current values of LowerFilters and UpperFilters.
If the disc is really unreadable, it might be wise to ask your father to send another copy, since there are no free tools for recovery. Anyway, here are some links to specialized CD recovery software: http://www.smart-projects.net/isobuster/
(ISO Buster) http://www.jufsoft.com/badcopy/
(BadCopy Pro) http://www.arrowkey.com/cddvddiagnostic.html
(CD/DVD Diagnostic) http://www.arrowkey.com/cdrxdataretriever.html
(CD Rx) http://www.naltech.com/
(CD Data Rescue) http://www.cdroller.com/
(CD Roller) http://www.elpros.si/CDCheck/
Sometimes such programs are used with RoadKill's Unstoppable Copier http://download.com.com/3000-2248-10155419.html
A recent comparison is available at http://www.ibo-business.com/ibo-cd-recovery-report.htm