First check whether the ball valve is open. If there is still no water flowing into the reservoir, there can be two causes.

1. The filter in the float valve is clogged. Unscrew the flexible hose from the float valve and remove the strainer. Rinse and reinstall it. Reconnect the flexible hose to the float valve.
2. The supply line is clogged. Flush the pipe or consult a certified installer.