Want to increase or decrease net book value or accumulated depreciation of assets

Hi,

We are currently using 12.0.4 version

How can i increase or decrease net book value or accumulated depreciation ?

Our fiscal year is starting from OCT-13 to SEPT-14

Requirement Example :

suppose i have an asset (Computer) Method  WDV 30%

Date in Server : 30-NOV-13

Cost : 24000

Net Book Value : 21146.29                                      IF increase in NBV  22000 or IF Decrease then 19000

YTD Depreciation : 2853.71

Accumulated Depreciation : 2853.71                       Same example of above mention increase or decrease

we want to increase or decrease accumulated depreciation or net book value

How can i do this ? need solution

Best Regards,

Sheryar.