How can I get my tolerance to alcohol back?

Okay so in October I partied too hard & drank too much at my friends birthday party. I blacked out & apparently spent the whole night puking. I had a pretty good tolerance to alcohol before that night. I can no longer stomach alcohol. I feel like a loser compared to my friends. I used to party so hard & win at drinking games but I can't now. That night ruined my party life lol. I went to a party a few weeks ago & I can't even drink vodka straight from the bottle. I had to mix it with stuff or I felt like I'd puke. I feel lame compared to my friends who can just chug Disaronno & smirnoff then I can't. So how do I get tolerance back ? I want to drink a lot again without getting sick. Also that night I partied too hard I took like 12 codeine. Could that have anything to do with it ?? Thanks.