How do I fix this myself?

Pulled forward to a curb so I could back up and I guess my license plate got caught on it and when I backed up, the bumper came undone a little. It looks like the screw hole widened. Would a zip tie do the trick.

 

I would get some new stainless steel nuts and bolts and use larger stainless steel fender washers to hold everything together with the holes being that much oversized.

 

you didnt just say ziptie that sucker XD haaa

 

Zipties? How ghetto.....

 

If it wasn't for zip ties half the trucks on the road would have fell apart. I used a bunch of em.

 

If I can’t fix it with duck tape and zip ties
It can’t be fixed

 

and if you can't fix it with a hammer, it's electrical.

I think I would try to do the same thing that got you here,
Only in reverse. Try to get against something and push it back together a little.
Then do the larger washer thing previously listed.

 

I think California and Illinois require the plate to be zip tied to the grill.

 

Upstate New York, too.

 

I second what @AModelCat recommended. Repair it correctly and use a proper size bolt and nut with washers. If you visit an actual hardware store you can get black zinc plated fasteners so it matches the color of the trim.