Do you get a 1099R form when you take a loan of 401k?

If you leave the company, you will get a 1099 saying you took a distribution. You only have until 60 days after you terminated to pay it back. However, if you can roll over your balance quickly enough, you might be able to borrow enough from your new 401K to pay off the old one. You only other hope is to find a way to borrow the money and pay it back. Beg you family. Get a second job if you must. A 1099 is going to be expensive as you will pay Federal plus state income taxes and Federal plus state penalties. You don;t say how much you make but it can easily amount to 40% or more. If you don't report it, they will come after you in a couple of years and you will owe interest and penalties on top of all that. Move quickly to pay it back before the 60 days are up, or there is no choice but to pay though the nose.

You won't get a 1099R form for the loan. You only get it for the distributions you take from account.

If you leave the job, then you will get a 1099R for what is left if you don't pay it off within a certain number of days after you leave.

You should not have been able to take a loan after you left the job. That'll be classified as a distribution, because there's no longer an income stream from which to extract payments. You'll have to pay it all back within 60 days.