You can restore the factory settings of the JD-990 by performing a factory reset.
CAUTION: All USER information will be lost. Be sure to back up any information you wish to keep.
- Press PERFORMANCE, PATCH, or RHYTHM.
- While holding down EXIT, press UTILITY.
- Press F6 (EXECUTE) followed by F5 (YES).
JD-990 Owner's Manual Download: https://www.roland.com/us/support/manual_archive/