You will not be able to do it with Lightroom.
The highlights mean there is no image data in those areas to restore.
I think your only hope is to do extensive cloning and brushing in Photoshop to 'paint in' the missing parts of the sign.
I think you can try to reduce the glare with the Highlights slider. Move this slider to the left side and check.
Take a look here:
Thanks, but I already tried that, and while it's helped me before, here is did not. But thanks anyway.
That's what I was afraid of. Guess it's time to take an online course in Photoshop. Thanks for your help.