How can i find some one who we havent seen since 1981?

Question:

How can i find some one who we havent seen since 1981?

Im trying to locate my dad, we have never met and i dont know anything solid about him accept the town he lived in 25 years ago when he was 15/16.
i dont know his previous address so i cant check the electoral roll, i dont know where (or exactly when) he was born so birth records are out too.
my mother is as much use as a wet bog roll and i dont know where to look next - a p.i is way out of my budget.
any suggestions?!

Additional Details

1 month ago
i am in the uk, so us sites are no good but thanks anyway! i dont have a credit card so subscription sites are very awkward

1 month ago
paradoxy.... i am on here for helpfull answers not ones like yours.
how the hell can you say its an unhealthy road to go down? have you been in my situation? you know nothing other than the brief details i have written on here - im not asking for half assed opinions.
also your last comments were unnecesarily nasty and pointless

Best Answer - Chosen by Asker: 1 month ago
i am in the uk, so us sites are no good but thanks anyway! i dont have a credit card so subscription sites are very awkward