Usually with a cold, the nose is blocked and words are not pronounced correctly and cleanly.

There is no fix for that kind of track.

I have had singers send me tracks for vocals that they wanted me to work with and possibly put better music to the track.
It was impossible.

On one, the singer was recording her voice on a cheap mic and she was obviously too far from the mic. Room noise was horrible and vocal quality was abysmal.

Another one, didn't record the vocal to anything that was tuned standard (A-440) nor did that singer bother to use a click track or metronome.... timing was all over the place. Stuff like that simply can not be fixed and singing with a bad cold falls into that same category.

I had to decline both asking them to redo the tracks a bit more professionally if they wanted a polished sounding project.... never heard from either again.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.