According to the search results, there are different events that happened to Spencer Reid in different contexts:

• In the Criminal Minds series, Reid was shot in the neck while trying to protect Blake and appeared to be critically wounded.
• In the Criminal Minds reboot, Criminal Minds: Evolution, Reid is absent because Matthew Gray Gubler, the actor who played Reid, was unable to commit to the full season due to scheduling conflicts with his other projects. The showrunner, Erica Messer, confirmed that Reid is still with the BAU, but he is simply away on a case.
• In terms of Reids addiction, there is no clear resolution in the series. In one episode, Reid takes drugs from Tobias body but doesnt use them because Gideon calls him. Hotch tells Prentiss that he has an agent that could have a drug problem, and everyone seems to know that hes struggling and is taking drugs, but they dont seem to ever help him or talk to him about it.
• In terms of Reids love life, he was reunited with his girlfriend, Maeve Donovan, in the season 12 episode "Lauren," but she was killed by an unsub, leaving Reid devastated by her death. In the Criminal Minds subreddit, some fans expressed their desire for Reid to find happiness and move on from Maeve.

Therefore, the answer to the question "what happened to Spencer Reid" depends on the context of the question. If it refers to the Criminal Minds series, Reid was shot in the neck while trying to protect Blake. If it refers to the Criminal Minds reboot, Reid is absent due to scheduling conflicts with the actors other projects. If it refers to Reids addiction or love life, there are different events that happened to him in the series.