Random apps keep installing on the phone Here is a screenshot of these apps. I never downloaded them:


Screenshot (click image for larger variant)

Many times these have been deleted by me but they are download as well as installed by themselves again and again. What should I do? Also, these apps I never installed all at once rather one by one.
There are several ways of trying to treat this.


Download some antivirus apps and see if they can find the app responsible. Unfortunately, this is not likely to be successful.
Run a factory reset. If the malware has not embedded itself into the operating system, a factory reset will delete whatever is causing this.
Flash the stock operating system. Almost all cases of viruses inside an Android device end up having to use this solution. By reflashing the stock operating system (essentially reinstalling Android), there is absolutely no chance the virus will survive the process. The stock ROM can be found  on the manufacturer website for almost all phones. Guides for how to flash ROMS exist for almost every popular phone ever produced. This is not for the faint of heart or those who are not good with computers. If this is the case, try to contact a friend who is. If the phone is still under warranty, this process will void it. Therefore, if I is under warranty, try to contact the manufacturer for repair first. 


Good luck!