How can I get an assignment back after wrongfully being flagged?

If you reenlisted for the assignment and you were wrongfully flagged, the flag must be closed favorably and the commander will need to write a statement explaining that you were wrongfully flagged, never should have been flagged, and were not at fault. If the assignment has already passed, or been filled by someone else, then it's gone. If you were placed on the assignment by the branch manager, then it's at their discretion to fill requisitions as they see fit.

Everyone is giving you sound advice. But add one more thing to that contact with HRC and or USAREC. When you make contact with the BDE Legal and S1, ask for a copy of the completed and signed DA 268 with Section III showing that the Flagg was closed out with Erroneous (Z). You may want to make sure that the Flagg Code submitted in eMilpo lifting the Flagg Action reflects as well. At that point you may have a better chance of getting through to your branch, but keep in mind, you may have still lost that assignment. It is generally speaking in the hands of the Branch Manager.

Good Luck!

Would definitely start by making sure the flag is closed out favorably. Contacting branch yourself might not be enough so if it were me, I’d have the commander right a memo explaining the issue and possibly having your 1SG or even better your CSM contact branch and fight for you.