I've accidentally deleted a number of contacts. How do I restore them so that they are still members of my organisation?
Short version, assuming you mean they are just in Trash, is
- go to Adv Search,
- tick the box for 'search in trash'
- select the ones to restore
- then under Actions choose 'restore from trash'
There are some instructions at https://docs.civicrm.org/user/en/latest/the-user-interface/undelete/