Can a Friend who provided a service, later ask for renumeration once the relationship has failed?

I spent 3 days repairing a friends derelict computer, and got it fully functional again. I spent several hrs also helping her to use it so it didn't get damaged again. Later, when she got home, she was unable to hook it up correctly. I told her I would be glad to come over and set it up. I spent more time on the phone checking to make sure plugs were in correctly, power cords etc.Then she said the letters were not working correctly on the web. I told her if could be the keyboard. Meantime, I asked her on several occasions to let me come over, look at it and either fix it, or find someone who could. All of which she refused. I than told her I had a brand new installed OS computer which I would give her free of charge, but she would have to let me have the one that didnt work and I would get it reinstalled, which would cost about $60. However, she was worred about keeping her old files even though I had them backed up. Can I bill her for 10hrs software repair (much less than it was)?