Help needed

[Turbo99]

I have bought some merchandise using bitcoin
A lot of years ago and when i was done shopping i had quite a bit of bitcoins left on my account. Only problem is that i am totally green i the sense how do i access my old account. Pretty important hense the amount of coins left on the damn thing It is like a pretty huge house. Any one ? help will be rewarded if it leads to i can re access my old account
Thank you