Restore old msdb backup(s) to a different db name. We typically add '_' and the date of the backup to the name. Something like this:
RESTORE DATABASE msdb_20190915 FROM DISK = 'x:\full\path\to\backup\folder\msdb.bak' WITH MOVE 'MSDBData' TO 'n:\full\path\of\where\to\put\restored\datafile\MSDBData_20190915.mdf', MOVE 'MSDBLog' TO 'l:\full\path\of\restored\logfile\MSDBLog_20190915.ldf'
SQL DBA,SQL Server MVP(07, 08, 09) Prosecutor James Blackburn, in closing argument in the Fatal Vision murders trial: "If in the future, you should cry a tear, cry one for them [the murder victims]. If in the future, you should say a prayer, say one for them. And if in the future, you should light a candle, light one for them."