What is the message that pops up when you try to message?
"Bummer, your messages have been disabled..."?
It may just be that the "customer" who tried to message you was a scammer and has been banned, which means you can't reply to them.
If you were sending messages to POTENTIAL customers (people who favourited your items, or messaging your competitor's customers through feedback) that would be why your messages have been disabled. If this is the case, it can be up to 2 months (or more) to get them back.
You can try contacting Etsy.
https://www.etsy.com/legal/sellers/
c. Communication Standards
i. Messages
With Etsy's "Messages", you have the ability to communicate directly with your buyers or other Etsy members. Messages are a great way for buyers to ask you questions about an item or an order.
Messages may not be used for the following activities:
- Sending unsolicited advertising or promotions, requests for donations or spam;
- Harassing or abusing another member or violating our Anti-Discrimination Policy;
- Contacting someone after they have explicitly asked you not to;
- Interfering with a transaction or the business of another member;
- Exchanging personal contact, financial or other information for the purposes of evading the checkout process on Etsy, including phone number, address, email, social media handles, external URLs, instructions for money transfer, etc.
