A driver holding a driving license issued by a foreign country having a long-term or permanent residence card is required to apply for a Czech national driving license within a period of 3 months. EU citizens and holders of any EU driving license are not required to do so as their licence is valid in the Czech Republic no matter the reason or length of their stay.
For all procedures relating to driving licenses, you will need to visit the corresponding department of your local authority. In the case of a lost driving license it is also necessary to visit the same authority and you will normally be given a certificate which will be valid for 30 days allowing you to drive only in the territory of the Czech Republic. Then within this 30 day period a new driving license will be issued.