Messed up my partition

[Erik Udo]

My boot loader wansn't working properly and i didn't find my 5.2.1
install cd, so i grabbed 4.4(or is that 4.6) install cd, and chose fdisk,
marked the freebsd partition bootable(S), and wrote changes.
I didn't notice that it had made my about 150GB partition as
100GB(ad0s3) and 60GB(unused) partitions.
After that i haven't touched the partitions.

I had one slice on that partition and i think it is dirty, i accidently
pressed the reset instead of the power button.

So i heard in  #freebsdhelp at EFnet that i could retrieve the data on that
partition by modifying the partition table(like the beginning and the 
end of the partition).
I dont know any probrams that could do this, or how to use them.

Here is some information about my HD:
-200GB maxtor

Offset       Size(MB)        End     Name  PType       Desc  Subtype    
Flags  

         0          0         62        -     12     unused        0
        63              20473   41929649    ad0s1      8    freebsd      
165         
  41929650        10236   62894474    ad0s2      7        fat       12
  62894475     100361  268435454    ad0s3      8    freebsd      165
 268435455      63409  398297087        -        12     unused        0

And please, answer me. this is rather important. I'll answer any 
questions as soon as i can.
Any help is greatly appreciated.