FYI, I corrupted my cryosparc_database while trying to reinstall as a different user. I will use cryosparcm backup before making changes in the future. Anyway, to recover the database, I stopped cryosparc and made a copy of the corrupt database directory (e.g., /home/user/recovery/cryosparc_database) and used mongod --repair
cryosparc2_master/deps_bundle/external/mongodb/bin/mongod --dbpath /home/user/recovery/cryosparc_database --repair
Then I copied the repaired cryosparc_database directory back to the cryosparc directory and restarted cryosparc.