dnd regain spell slots

To cast one of your warlock spells of 1st level or higher, you must expend a spell slot. You regain all expended spell slots when you finish a short or long rest.

Character optimization guide for the DnD 5e Ranger's spell list.

As a Druid, you gain the following spell slots when you reach the specified Druid levels. These spell slots are listed in the Druid Spell Slots table.