I find if I’m not feeling it or them I either completely mangle them and try to get something different out of them or swap them out. Something fresh in the banks can get things moving again
For example- If you’ve got something in the sampler try setting a super short loop point to create a note you can play. Add heaps of effects and resample it and try the same again. You’ll end up miles from where you started and it may ignite a spark that gets you going. It might not of course but you will have been ‘creative’ along the way.
That said, if I’m not ‘feeling it’ at all I’ll try doing something else for a while and come back to it. Can’t be creative all the time and I definitely can’t force it if I’m not there.