You will have access to all druid spells, not just through level 3. Like I stated earlier, first it determines which lists you have access to (and technically, you have access to the entire list; you just don't have any spell slots assigned yet), then determines which spell slots you have based upon your classes. Thus, to make a long story short, you will have access to all druid and all cleric spells as soon as the ranger class reactivates, and then the game determines which spell slots you have based upon your level. So you will have full access to both druid and cleric spells of any level.

Just one more question: what about the number of spells you can cast per day? For example a level 12 ranger can cast 2 level1 spells 2 level2 spells and 1 level3 spell. Do these get added to your cleric spells once you regain your ranger levels?

Also is cleric dualled to ranger possible? And in that case will he get both clerical and druid spells? and how many spells per day can he cast then?

Your # of spells per day are determined by your cleric class (plus wisdom modifiers, if any).