Hi:
There’s a list of actions that will trigger a temporary play restriction automatically… here: Blizzard Support - Temporary Play Restrictions in Diablo II (2000) . There’s also this pinned post at the top of the forum: [Diablo II] Temporary Restrictions .
I think that Blizzard Forum Support Agents can tell whether you have one or not… and, if you have one, you would need to submit a ticket to find out when it will end. Normally, that’s not a big deal but right now is a bad time to put a ticket in because the ticket response time is approx. 2 weeks, sometimes more.
Have you tried all the suggested troubleshooting in that Support note I linked above ?
You could wait a few days and see if it goes away.