I recently became widowed. I have never forgotten my first love in high school after 45 years. I have been in contact with him and would like to become friends with him once again. What do you think I should do? I think the high school love was more on my part. Since he still talks to me, do you think I have a chance of becoming involved with him.

I think life is too short to spend much time speculating on "what if". I think if he is a single guy then there's no harm in exploring this but I also think we make problems for ourselves when we enter situations with expectations.
You knew this man, was he sensitive or a jerk in high school. It's likely he's the same type of person, just older. Is he someone you can be vulnerable with? Maybe it's too soon to be vulnerable and you just want to be friends until you know who he has become. You can set your boundaries and the terms of your relationships and only you can decide if the timing is right or not. You know in your heart if you have a chance or not so just be honest with yourself about it. If this is just friendship then be glad for the friendship... I've always found friends a lot harder to come by than lovers anyway.
Just my opinions.

I'd go for it... you don't have anything to loose right. First, I'd make sure he isn't already married though.

Id go for it if he's single... its crazy how your high school loves mean so much :D

Yeh ditto. Go for it. If he has a family, wife etc be cautious. Maybe you can be friends in that case?

Anyway what an amazing feeling to be in contact with someone after so long. Good luck ;)