Sheet Reference Problem, Formula suddenly referencing wrong sheet

Hi Guys,

I consider myself a proficient excel user. I have a very large work book that has many sheets and some reasonably complex equations, etc.

For some reason all the sheet referencing has suddenly gone out of sequence. For example an equation on Sheet 1 that was referencing Sheet 2 is now referencing Sheet 3. An equation referencing Sheet 3 is now referencing Sheet 4, so on and so forth.

Given the complexity of the workbook it is an enormous task to correct this cell by cell.

Has anyone ever come across a similar problem?

Can anyone help with a global fix please?

Thanks!

Thanks CK76!

Bit of lateral thinking.