What you reported doesn't requires a reinstallation of any FSDT product and it won't be fixed by it.
Assuming what you did resulted in the loss of your customization for for KLAX, this would revert to the profile supplied with the scenery, which surely has all the jetways in place. If it doesn't, the problem is likely GSX is not seeing the FSDT AFCAD, but another scenery in conflict, so it's not activating our profile, but one for the conflicting scenery.
You can verify this by checking the GSX customization page and see if the name of the AFCAD in use is the one that comes with our scenery. Note that, if the name is right, when we do updates, usually the AFCAD and the GSX profile should go together, so you should always ALLOW the AFCAD to be overwritten when asked.
We added the option to ask the user before overwriting the AFCAD, to allow user modifications but, it's possible that ( assuming you *have* customized the AFCAD ), if you did it from an AFCAD that was made a while ago, possibly before we added SODE/GSX jetways to the scenery, and you are not allowing the FSDT Live Update to overwrite it, the new GSX profile that we made for the current AFCAD, might not entirely compatible with the old version you based your customization from.
A conflicting scenery for the same airport or an outdated AFCAD that you haven't allowed to overwrite are the only possible reasons why the scenery and the GSX jetways don't match. Assuming you *are* using the GSX customization that comes with KLAX.