Only Administrators are able to access the Recovery Bin
Additional filtering options are available by selecting Filter on the right
Recovery of deleted items is not guaranteed
To recover multiple items check the boxes on the left, Recover from the Action drop-down, and then Apply
If the Matter is missing but you don't see it in the Recovery Bin, the permissions on that Matter may have been restricted to a specific user. In this case, check with other users in your account to see if they have access to the Matter. If they do, then I recommend going into their Account and updating the Matter Permissions to allow access for all users [see steps here].