Hi I have a friend who is imprissoned and am willing to contact him. I have been trying to find his details with failure... If I sent a letter addressed with only his name and the prison adresse would it reach hi or not

Many thanks stew

It might. Write a short note and put your return name and address on the envelope and you will either get it back, or get an answer from him, or he won't get it and you won't get it back, or he will get it and he won't write back. Generally first class mail is not tossed out by prisons as far as I know, so you should at least get it back.

What's the name of the prison.

Most institions have a website. One of the things on such a website might be how to contact an inmate.