Why the wells have gone dry? ...

Why the wells have gone dry? May be its a result of over-lifting of water. Hydrofracturing is a good way to retap the water. Hydrofracturing is a well development process that involves injecting water under high pressure into a bedrock formation via the well. This is intended to increase the size and extent of existing bedrock fractures, pumping water into those fractures at pressures as high as 3000 psi and flow rates as high as 85 gallons per minute, this cleans out the fractures and allows them to interconnect with nearby water bearing fractures. Water can then flow back thru these fractures and into the well at a faster rate than before. thou its a expensive method but if there is plenty amount of water available in the aquifer I suggest you should go for it. Rather constructing new wells.