After you file

PDF or paper copy  (or IRS transcript) of your originally filed tax return is required to amend properly.

The Schedule C will show the expenses you deducted. You reenter those the best you can.

 

IRS will give you paper copy of prior returns for a $43 or $30 fee, depending on which webpage you look at.

It's not clear how long you will wait for it.

@sept031989