Q: Apple ID problem

Around two years ago I decided that I want to change my Apple ID. I decided to do this as I was thinking of changing my internet provider and every thing was linked to them. I now have a updated ID and password. There has been no problems over the last two phone upgrades till this week when I moved into iphone 6s Plus. It keeps asking me for the password for the apple id that I had over two years ago. I can't remember this password due to time. So I went onto apple web site to redo the password but it tells me that it does not recognize that  Apple ID. So I then decided that I would do a restore as this has fixed most problems in the past. What happens is I get to part 6 of 6 in iTunes and just before it finishes it just stops. This is to the point that I have to force quit iTunes as there is nothing else I can do. About 15 percent of my apps are greyed out as they don't get installed. Some of these apps I have had to manually installed and some I can't get installed. I hope that if I can get my password rest for the Apple ID that I had a long time ago might help me get things installed. Is there any way that I can change a password on an Apple ID thats not current.