How to Unsplit a polysurface?

Hey guys,
How can I unsplit this face? I was working on another part of the model and must have accidently projected and split this part. This was during a previous session so I cant just ctrl z my way back. How can I remove this split? Untrim and merge edge doesn’t seem to work.

Thanks

If the object split was a polysurface, not a single surface, then:
Explode both split polysurfaces into individual surfaces
Untrim the individual surfaces which were trimmed by the split.
There will be duplicate surfaces. For each pair of duplicates select one and delete. Or use SelDup and delete the selected surfaces.
Join the individual surfaces to create a polysurface.

Great thanks this seems to work well. A little tedious but if its the only way its something!
Thanks again,
Luke