It looks like you may be offline. Without further information or a photo it is difficult for me to provide the best advice but I will certainly try. Please reply when you can and we can continue the conversation.
Kittens often misjudge jumps or fall from furniture and it is not unusual for them to strain muscles.
They can be quite lame but with rest and a little time, most improve quickly.
They should be able to bear some weight and should still be active, playful and happy to eat.
However, if signs are not improving quickly (within a day or two), if they are not bearing weight, if they seem depressed or in pain or if there is visible swelling, then a vet trip is needed.
If concerned, the vet can perform an x-ray to check for any fractures or dislocations.
The vet can also issue some anti inflammatories and pain relief if needed.
At home, encourage strict rest, to avoid excess pressure on her leg.