Теория:

Study the information about the 2nd Conditional.
  
Type 2 Conditionals.
  
This type of conditionals expresses an improbable and imaginary situation
which is unlikely to happen in the present or future.

Use this structure:

If + Past Simple, would / come/ might + bare infinitive

If I had a lot of money, I would buy a new car.
 
shutterstock_794159299.jpg

You can use were instead of was after if.

If I were you, I would talk to him.

If Sam was/ were here, he would tell us how to react in this situation.
 
shutterstock_314857217.jpg