From only the description you've provided so far it sounds as though there is a large number of orphaned jobs. Please follow the steps outlined below. This will clear out any orphaned jobs.
- Stop the "SolarWinds Job Engine v2" Windows service
- Go to "C:\ProgramData\SolarWinds\Installers"
- Run JobEngine.v2.msi and, choose "Remove"
- Run the "JobEngine.v2.msi" again, and choose "typical install"
- Start the "SolarWinds Job Engine v2" Windows Service.