I cannot use my phone properly

Sometime I am facing touch problem ,I cannot touch my side screen means when I touch it it doesn't give any response and sometime I am facing ghost touch problem.I am also suffering from battery problem.Although I put software many a time by Lenovo executive in my phone,this phone is too slow to open a app or intall , download and uninstall a app.It also lost signal many a time and sometimes those apps that is easy to continue for a 2gb ram phone,it cannot runs those apps or hanging and lagging when I open it.Sir my phone name is Lenovo k50a40 k3 note