Hello @Karthikayini M.
First of all run the command java -version on the command prompt to know the availability and version of Java.
If you do not have a Java then install it the version required by Dynatrace Client and then in the Advanced System Settings assign a veriable e.g.
The client installer installs a private JRE into the Dynatrace directory already so there should be no reason to have to install a Java Runtime.
If you're still having problems, perhaps you should uninstall and then reinstall the client.
Can you clarify whether you're using locally installed client, or the JNLP client?
I suggest you delete the client you have and install the full client from the downloads page. It will install a JRE for you as part of the client install.