You have received great advice from our staff and members.
As you’ve now discovered, extension is the hardest thing to recover when you’ve had a bad knee for a long time. I wish I could tell you that there is a miracle cure out there, but the only miracle is patience, if you can embrace it. All those soft tissues don’t want to change and you must allow them to stretch back out at their own pace. Forcing and “working hard” isn’t helpful. But, what IS important is consistency with gradual challenges added as you are comfortable doing them. Be sure to concentrate on a good, long stride when you walk. Do the “hang” exercises daily that let gravity help straighten your leg in gradually longer times. Try not to get discouraged and don’t feel bad if it’s more comfortable to use a cane or walking aid at times. Better to do that than to get tired and walk incorrectly or not walk at all because of discomfort. Keep your eye on the goal and you’ll get there. But for this party, it’s your body that’s in charge….not you.
As for going back to work, you’ll need to find what will work best for you. Perhaps you could stay off a little longer. Or possibly work part days or have an accommodation at work for a while. It’s worth discussing with your employer. Offer reassurance that this situation, while it could last a while, is temporary.