Do you mean the disk itself or the code? And by OEM I assume you mean one of
these? Anyway you should be able to install windows any number of times from any disk/media, hell you can even legally download the .iso for any version in any language of windows, but the activation code can only be used once (although people just treat OEM disks as 'only one PC at any one time' anyway). It is possible to recover the activation code used for that copy of windows, I think it'll still work with pre-installed versions.
What do you mean by could not use the disk though.