I know how you must feel. Don't give up, no matter how slim your chances are!
3 Months ago I talked to a guy on Chatroulette till our connection got disconnected, sadly. All I was left with was his first name and the city he lived in. 5 weeks and a LOT of effort later I found him :-)
I hope this gives you a better feeling! You got it easy in comparison to me! Don't just go to the bar on the same day and time as when you met, hang out there more often :)
You can go to the same bar at the same time and the same day to see if he shows up. If I was interested that's what I would do in hopes you would show up. You can even go to the bar and ask the bartender if he knows him. Leave your first name and number with the bartender in case he shows up if he returns some other time.
If he shows up, the first thing is exchange didgets. Lol
Just go back to the bar a couple times. Chances are that he'll be back.
Try going back to the bar and asking the bartender about him. Maybe he is a regular. Bartenders know everything.
i would revisit that bar the same day of the week at the same time of day/nite hoping he's a regular at that bar...that imo is your best shot to reunite with him.
Best of luck, and I hope you learned your lesson about always getting contact info.
Do you know his last name or have mutual friends? Maybe you can find him on Facebook. Also, Craigslist has a "missed connections" section.