How do you work in a situation if the plant is stock out?

Did you mean if the plant is out of stock? Warehouse out of stock? 

If that is the case then there is something called a rain check. As soon as the product is in stock you can send client their order.

If client is in need of the order and can not wait until you get the order and restock then its possible to send the client their order straight from the manufacturer that you deal with. 

Correct me if I am wrong, procurement isn't my specialty and would be nice to learn. 

agree with Kathy Mustafa  

Thanks to all for given anwers

That's not really my field of work but thank you for the invitation )))

I agree with my colleagues answers

I echo with Kathy on out of stock warehouse situation..

You can arrange the material form other plant  to prevent the immobilization  of stock out plant.

then you can further process to order .

agree with the answer

We can take loan from sister industries to resolve the shortfall. Indeed there are stockists in the market who can help on most emergent basis. Workers can be divided according to priority and a stock out situation thus can be handled.