It should not be necessary to restart the Qlik services as these are not holding the lock.
In the task manager, you should find one or more qv.exe processes (QV Desktop) and/or qvb.exe processes (publisher/server task batch executables). One of these is possibly frozen, but still holding a lock on the QVD.
Close all instances of the desktop and/or terminate or wait for server/publisher reload tasks to finish.
Any qv.exe or qvb.exe remaining may be frozen. You can terminate (at your own risk) this process in the task manager which will release the lock.
Logic will get you from a to b. Imagination will take you everywhere. - A Einstein