Just show love. If you continue to show love, in spite of what happened, eventually, it will be mended.

Have a heart to heart talk and find out if the friendship can be restored.

Send a funny card, beg forgivnesss, blame it on hormones, give it time, have a good laugh and try harder!!
Or re-evaluate the friendship. I have had times in my life where certain friendships were too much work. It felt freeing to step away, occasionaly for good.

I find that giving someone, whether family member or friend, some time and space allows both parties to think things over and try harder to make things work.

Honestly, I think you need to consider how much energy its taking to maintain this relationship. Did you do something that needs an apology, or is this a recurring theme in the relationship. It might not be a good match. I think friendship shouldn’t feel like a chore, and I choose to maintain relationships with women who are going to be OK with me not calling for a month or so if things are really crazy.. but when I do, we can pick right up where we left off.

Otherwise, I think going out to lunch is always a good fix!