While I'm sure it seems to you that you've somehow disabled your LG TV with your actions to hack your DVD player with a universal remote, I'd say it's more of a coincidence that the LG has decided to stop working via the remote. There is nothing you could've done with that universal that would effectively shut off the remote functions on the LG, especially since your initial instructions told you to put the universal into the DVD mode.
A universal remote is like an interpreter. It can speak many languages but you have to tell it what language it has to talk in order for the listener (TV, DVD, cable box, etc) can understand it. In order for you to have somehow done something to the LG you would've had to programmed the univeral to work with the LG TV first. Then, you would've had to screw up the hack directions which specifically tell you to switch it (the universal) to the DVD mode of operation. Then, somehow, the directions for hacking the DVD player for multi-region operation would wind up disabling the remote functions of the TV set. (I'm not even certain this is possible). In fact, the few steps of the directions you have listed are merely for setting up the universal remote to work with a Sony DVD player, the remote itself doesn't even send out a signal during this phase of the setup process. As you can see, it's more plausible that the LG remote or TV has decided to choose this particular moment to go on the fritz.
I'd start by making sure you have good batteries in the LG remote. You could then take the remote into a shop and have them test the thing to make sure it's even sending out a signal. 3rd, last but not least, you may have to resort to taking the set into a shop for service.