I forgot to put the lid on my can of paint and left it open overnight. Looks like there is a little bit of skin on the top but it hasn't completely dried out. Can this paint be saved??
Most old paints can be saved, (albeit at a drop in final quality) as long as you can squish it somehow, and add in more carrier (thinner or water). The final colour is generally a good enough match, but blobs can make it annoying.
I had enough for a touchup, but it was a putty-like consistency. It did take a good half-hour of mashing with various implements and slowly adding water, but the resulting mess worked well enough, and went on thicker than the original paint, which was nice because it helped smooth the underlying blemishes in the wood.
The skin is done-for in your case, but peel it off, and try to wipe the underside on the lip of the can, so the not-dry paint falls back into the can.