In order to Restart Qlik server's services please follow the below steps.
Open task manager and go to services tab.
Find repository database service and press stop. It automatically stops all Qlik services.
Now in order to start them again you need to follow the below sequence.
1. Qlik Sense Repository Database (QRD)
2. Qlik Sense Service Dispatcher (QSD)
3. Qlik Sense Repository Service (QRS)
4. Qlik Sense Proxy Service (QPS), Qlik Sense Engine Service (QES), Qlik Sense Scheduler Service (QSS), and Qlik Sense Printing Service (QPR) in no specific order.
These are the official instructions found in Qlik's manual.