reinstallation of mmc and snapins

Well I dont know exactly how this happened but I can no
longer access mmc or any snap-ins on a client's system.
Specifically they no longer exist in the system root.
I figured the 'quick fix' would be to apply SP4 and then
it would be replaced. Well SP4 has already been applied
and my W2K OEM disk is only SP3 so I couldnt use that to
upgrade or 'refresh' the original files. Im not sure
exactly how to 'rollback' the service pack successfully
but it seems that is the solution. The only other way I
can think of is to replace them manually in safe mode but
I dont think I can get all the \com\ and other related
files without considerable study and time using another
system. If anyone has some tips help me out...Id greatly
appreciate it
(E-Mail Removed) Im almost always monitoring