Hmmm… First, how about opening one of the previous auto-save .pproj files?
In CS3, the dynamic link is only an output from AE, so your “friend” would have needed to export the PPro sequence (as an AVI let’s say) so that he could bring it into AE to work on. The “Capture Linked Comp 01/Rabih Haddad.aep” is that AE dynamic link, and it would show the resulting CC work he/you performed in AE. So your original tracks or merged-tracks should still be accesible. What footage comprises the AE project?
Also, the “Capture Linked Comp 01/Rabih Haddad.aep” should have been placed in a new sequence, and there would have been no need to delete the original sequence. Are you sure the old sequence is not hiding in the project bin somewhere?