The Commonwealth ruled from 1649 to 1660, during this period Parliament was in control but the real power rested with Cromwell and the British Army.
The Restoration came when Charle’s son landed in Scotland and declared himself Charles II and invaded England.
The Restoration was offered if Charles II agreed to religious toleration and general amnesty, he agreed with the proposals. He was crowned Charles II and ruled from 1660-85.
After the fall of the Western Roman Empire, Europe sank into a 700 year period of instability and then began a gradual recovery that led to the Renaissance.