So you made a vet twink, let your account time run out and holy shit, now you cant que BGs. Welp, thats because Veteran accounts (and F2P accounts) cant que BGs with XP turned off and you didnt turn your XP back on before your account wound down. You'll have to open a ticket and get a GM to turn it back on for you. Good luck!
I'm including the following script courtesy of Zwab from the XPOff discord that he recently used to get this problem resolved. It includes a link to a battle.net support article on this very topic. Feel free to use it when contacting GMs
https://us.battle.net/support/en/article/20294 The article states the following: "Re-enable experience gains without adding game time by talking to Behsten in Stormwind or to Slahtz in Orgrimmar. If this doesn't re-enable experience gains for you, contact us." I have talked to Slahtz in Orgrimmar, however he took 10 gold from me and did not re-enable my experience gains. I am now contacting you regarding this issue as stated in the article, are you able to resolve my issue with experience gains? Thanks.