Correction of fixed asset register

Does anybody know how to correct values in a fixed asset register when :

- the origin of the problem lies in a closed fiscal year (3 years before current).

- For the involved depreciation area, there was no match between accounting and asset accounting in the year of the problem. So, accounting is right, fixed assets register is wrong.

Reset of the fixed asset register is not an option since the company code is no longer in test.

Thanks for your help.

José Beghein