phone slow and have doubt

[smilysahul]

After July I have doubt that I have attacked by some malware or some other. But I'm not sure about that. I have got that doubt because 

1) phone is some what slow 

2) some thing is downloading but within seeing that it was dissappearing. Even though I seen that  fastly there was no detail on the top. It is not going anywhere if I touched that noticification also

3) yesterday I have seen one thing. While playing games( on Flipkart) , the display comes with some black bubbles( moving from place to place) at some places and went after some time.

Can I do the reset, to come out from this problem. 

Mobile model: A20

[brijkishor1982]

ok thank you

[Samsung_Support3]

Dear Samsung Member,

Greetings from Samsung Customer Support!

To resolve your device hanging issue please visit this link: https://www.samsung.com/in/support/mobile-devices/how-to-restart-the-device-when-freezed-or-hanged/

For further assistance, register your concern in Samsung Members Application (Open Samsung Members Application > Get help > Send Feedback > Error report/Ask questions).

Thank you for writing to Samsung.

Warm Regards,
Samsung Customer Support