I have a very low water level in the toilet BOWL. How can I fix this problem?

I have a very low water level in the toilet BOWL. How can I fix this problem?
I have a very low water level in the toilet bowl... how can I correct this problem?

Inside the toilet thank is one piece of metal at one end has one big black ball and on the other end is the valve pressure u just has to adjust it, piece of cake!

I have a very low water level in the toilet bowl...how can I correct this problem?
Your water level should be 1/2" under the top of the white overflow tube when the tank's filled and the ballcock shut down. Make very sure the small tube that comes out of the top of the ballcock is connected to the white overflow tube. This small tube is part of the bowl fill. Let me know , Tom