Lightroom Library Help!?!?

[prodigy2k7]

I need some help. I don't know where to ask this, sorry if its in wrong section.

I have all my stuff on an external hard drive. So yes I unplug it and plug it in all the time. So the drive letter changes. Ex: G:\ or H:\ etc... So in the lightroom library the letter changes... How do I combine all of them into the same letter. I don't want to delete anything!