read voltage by analog pin problem

I used the arduino Uno to read the water level sensor voltage (0-5 V) by analog pin A0 . every things

at OK but after three or four days the Angelo pin begin read 0 or not true value and I check the true

input voltage value by voltmeter its real read . and when I pressed the reset button on Arduino Uno

the read for the voltage come back true . can any one help me.

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@fayez2876s, do not cross-post. Other thread removed.