Exchangeing Bread

I bought bread at a grocery store.

You can also say 'supermarket' or 'grocers' although grocers is a slightly old word nowadays, also grocery store is American English.

I got home and then noticed that the package ofing for the bread was torn.

I thought I broke it on my way home, but the bread had already becaome dry and hard, so I figured out the packageing was torn before I bought it.

I forgot to buy milk too, so I went back to the grocery store and had ithe bread exchanged for a new one and bought milk.

Since 'milk' is the last noun you referred to, at first it sounded to me like you were exchanging milk and not bread. After re-reading I understood, but its easier to read with my correction.

I'll make sure if the packages areing is ok before buying it.

Usually we use 'package' for a small item to be posted in the mail, packaging is the plastic around a product.