Hi Lydia. Usually, when you get the "media offline" filler, it indicates Premiere Pro cannot find the original media in the location it was expecting it.
Has the media been moved? Or perhaps a drive designation changed?
If you still have the media, all is not lost. Premiere Pro just needs to know where to find it. I do not have CS4 in front of me, so I may not have the exact menu terminology, but we should be able to get close.
Find the media clip(s) in your bin, right-click them, and select "relink". Now you can locate the original media and link it back to the project. It should then re-appear in your timeline and monitors.
Dell Precision T7600 (x2)
Win 7 64-bit
Adobe CC 2014 (as of 7/2015)
256GB SSD system drive
4 internal media drives RAID 5
Typically cutting short form from HD MP4 and P2 MXF.