When i m trying to send message to any sellers it returned to an error that user is blocked ?

Hello,

May be you're using ebay.com, try changing to ebay.in . (Switching sites will enable messaging if you're an Indian registered seller)

Dear sa-9198,

We regret the inconvenience caused.

Inorder to solve the issue faced, we request you to kindly connect with the eBay customer support team by visiting the following link:

https://www.ebay.com/help/call_us?type=ContactUs&initFrom=HOME&topicId=4000

Make sure you are selecting the appropriate reason of contact so that you can be directed to the correct method of support i.e. email/chat/call.

Regards,
eBay IN CBT Team

open in new tab - Ebay.in and log in there first and keep that tap open for some time...If possible click on "Keep login" 

now click on reply ..it will never show you that error.