Just got home from knee reconstruction sgy my femoral nerve cath disconnected what should I do?

Call your doctor. Dr g's answer is correct but u should have received a paper before you left to tell you what to do and give u a number to call. This can be a serous situation if the catherter is exposed to dirt u an infection gets into the groin. Deal with it immediately do not wait. Call your doctor now.
Remove it. First and foremost-don't worry! simply pull the catheter out and place a bandage over the exit site. The downside is that you'll lose some hours of pain relief as you will no longer have local anesthetic infusing. But, this is preferable to you trying to reconnect the infusion pump to the catheter. Good luck with your recovery.
Reconnect it. If the tubing is disconnected, just reconnect it. If the catheter is dislodged or coming out, you might as well remove it completely. You should still have some pain relief now, but it may wear off if the catheter moved at all. Reconnect it and you may be able to continue as previously directed. You may need to start oral pain medicine if you have pain. Feel free to call your physician.
Call doctor. Lijely you will be told to clean the connection with alcohol and reconnect. Still i would suggest paging the on call doctor to discuss what happened.
Call anesthesiologis. You should have been provided with a contact number for the anesthesia service. In the hospital I have carefully disinfected the catheter, trimmed the end and reconnected it. However, not all catheters will allow this. Your anesthesiologist will give you instructions on cleaning or removing it based on their expertise and your specific needs.