VGA help please

[Rubir]

My monitor appears to be working and connected properly but when I turn it on the message reads vga input no input signal. Have done all the usual things unplug/ replug etc. it worked fine initially but went blank when I tried to connect to internet site
Please help!!!
Ruth

 

[Seventh]

Try to change your vga cable or use a different monitor, if that doesn't work check your system unit...