After reviewing the information provided I understand that your account is under review for inauthentic complaints you have received.
As per Amazon polices you need to have all the necessary documents of the products before you list them on Amazon. As you mentioned you will not be able to provide invoices mention the reason why you cannot provide invoices and later proceed with a strong plan of to get your account reactivated.
Below are some points which will help you to construct an effective plan of action:
Reason for which you do not have invoices to provide?
Why did you receive the inauthentic complaint? Give the details like you have mentioned in the post that you have packed a wrong item.
Did you had any conversation with the buyer regarding the complaint, if yes provide the details what made the buyer to complaint against you?
Now that you are aware that you need to have invoices what steps you would take to resolve the issue immediately.
When you received this inauthentic complaint, what have you done to rectify the same?
How did you help the buyer to resolve the query when they reached out to you when they were not happy with the service?
How will you verify that you are procuring the products from the authentic supplier?
How will you ensure Amazon that you will send the correct product and not a different one in the near future?
What proactive steps will you take to ensure items are sourced from reliable suppliers?
Have you taken all appropriate steps and quality checks to ensure that the product being shipped is the correct one with proper packaging to avoid damage?
Make sure you implement the changes before providing the Plan of action.
To send the appeal follow the below path: Seller central home page >> Performance tab >> Performance Notification >> Check the email which Amazon sent while deactivating your account >> Send your details through the “Appeal” option so that the performance team reviews the same.
Provide the required details, so that the team can review and help you with the account.