isolating vocal parts from sheet music

My problem seems even more basic, yet I can't yet solve it
I am NOT a musician , but I sing in a SATB chorus. My ability to read music is poor.
It is excruciatingly slow for me to plink out notes on my home keyboard.

There was a program -Smart Score that promised to scan and play sheet music, isolate parts, etc, but it never worked.

When I try to use Play score (one page at a time!)to import XML into Musescore, I see a message that the files are corrupted.
Has anybody got this figured out???

Frank