To find out negative spid in sql server, you can use below query. This query will give the negative spid and kill command.
Copy this command and execute against master database to kill negative spid.
select distinct convert (smallint, req_spid) As spid, DB_NAME(rsc_dbid) As dbname, 'kill '''+ cast (req_transactionUOW as varchar(50)) +'''' as KillCommand from master.dbo.syslockinfo where req_spid < 0 and req_transactionUOW <> '00000000-0000-0000-0000-000000000000'
Output will give you the kill command of negative spid