Just knock 10% off your current 5x5 and then work back up like normal.
So if you were squatting 225, knock off about 25 pounds and go back to 195/200, then increase 5 pounds per workout like normal.
Then when you get back to 225, you can decide to keep doing 5 pound jumps or 2.5 pound jumps.
This may help for reference:
How to Break Plateaus on Stronglifts 55 | StrongliftsYou get back to where you left off fairly quickly but sometimes the reset helps your form improve or gives your CNS a little break from pushing yourself to the max.
If you do that 2 or 3 times and are still stuck, then you can try going down to a 3x5 for whatever lift is stuck. Then if you plateau after that, probably time for a new program.