You can try reiserfsprogs utils from
http://www.namesys.com/download.html
but I suggest you to back up your linux partition into another hdd, repartition again, and restore from the backup. (you can use a Knoppix or another LiveCD for the backup, refdisk and restore procedure. it is the safest solution IMHO).
Anyway, in both cases a backup will not be unwise :-)
Hope I could helped.