Soulseek process's most likely still running in background, try to end it via Task Manager first and than restart it again. Windows 10/11 Task Manager can be a bit cumbersome for finding the desired process/task, so give it a try via the Details tab, sorting the running apps by Name and then looking for the Soulseek process - it it's there, just right-click it and end it from the corresponding context menu action.