Missing Student Kicked Out of Luke Bryan's Bar Seen on Surveillance Video

A college student who's been missing since Friday -- this after getting asked to leave Luke Bryan's Nashville bar -- wandered the streets aimlessly ... now seen on surveillance video.

22-year-old Riley Strain was in town last weekend, visiting with friends from the University of Missouri for a convention in Nashville -- and they went out drinking Friday night ... hitting up Luke's famous 32 Bridge bar, where cops say he got kicked out after being overserved.

Strain reportedly told his friends he'd just walk the 5 blocks back to their hotel and meet them there afterward ... but his buddies say he never turned up, having totally vanished.

Now, the police are on the case ... and they're asking the public to help locate Riley since he still hasn't turned all these days later. Nashville PD also posted some surveillance video that was captured that night, which they say shows Riley stumbling around all by himself.

The guy's said to be well over 6 feet, so he's hard to miss -- and in these videos, you see him cruising the streets almost without much direction or purpose. In one video, you see him cross the street alongside a group of people ... and he comes across as out of control.

In another video, you can see him running, and even falls briefly. On its face, it appears he's under the influence -- which his why him going missing like this is all the more horrifying.

As for Luke himself ... he's addressed this story, taking to social media to write, "Y'all This Is Scary. Praying For His Safe Return." LB also noted his bar was cooperating with the authorities in their investigation, while also sending their thoughts and prayers to his fam.

The story has started to get national attention, and billboards in the area have already gone up advertising his disappearance. His parents have said they're incredibly worried about his well-being, calling this whole ordeal an utter nightmare. There's no question, it 100% is.