Showing Minus QTY on Hand

In have create issued some delivery note against some specific inventory items. Now QTY hand of these specific item is Minus.

Why this and how to resolve?

The quantity on hand is calculated as the sum of the quantities on Goods Received Notes minus the sum of quantities on Delivery Notes

So you have recorded more units physically delivered than you physically received - which is impossible

Either you have neglected to record some goods received or you have recorded some deliveries twice or more