If you have a credit card and are not using it then eventually the credit card may be suspended by the credit card company.
The only way to keep the credit card from being suspended due to inactivity is to use it at least somewhat for small purchases and then pay off the balance.
So use your credit card to make a few purchases such as groceries or gasoline and then you can pay back the balance in full.
Using the credit card and paying it back in full will help to improve your credit score and keep it from being suspended due to inactivity.
If the credit card is suspended due to inactivity then you can call the credit card company to have the credit card reactivated again.
Just be sure to use the credit card for some purchases to keep the credit card active.