All the things that you mentioned are part of the structure and are counted as improvements, except appliances. Built-in appliances that are attached to the structure are improvements. But most kitchen appliances (at least in the United States) are not built-in, and therefore are not improvements.
Receipts or other records are needed not only to show that you made the improvements, but also to establish the cost. If the appliances are not built-in, it won't matter that you don't have receipts for those, since they are not improvements. But you obviously had major other costs for improvements. I again recommend that you consult a tax professional. The tax pro will advise you on how you can handle significant costs for which you have no records.
