If you can, find your recording first as it is easier to choose by listening, rather than by looking at the score.
Once you have chosen a recording, use the Library Catalog to find the matching score.
Limit your search in the Library Catalog by MATERIAL TYPE to MUSIC SCORES for better results.
Include an instrument in your search. You'll get much better results searching for SOLO and VIOLIN than just SOLO MUSIC.
Certain musical forms are typically written for a single instrument, including PARTITAS and FANTASIAS. Sometimes SONATAS are for solo instrument, but sometime they are accompanied.
Click on the Score and Media Search link below for a tutorial on finding scores in the Library Catalog.