MBR and slices

[horn]

After reintalling windows i want to install FreeBSD boot loader
(/boot/boot0), after the second operation of record of the loader is carried 
out writes about the following (precisely I do not remember that wrote 
fdisk):
MBR not write 
Invalid Geom

Esteemed handbook and has tried by means of boot0cfg to put, i wrote the 
following:
# boot0cfg -s 2 ad0
Has not helped too though the loader was, but the chosen system was not 
loaded.
I tried to replace number of slice:
# boot0cfg -s 1 ad0 
Besides the loader was, but the chosen system was not loaded. Has then found 
out that sections on slice at disk ad0 have flied all, on this disk the 
system has been installed.

Whether it is possible to restore a disk or even the information therefrom?