QB Issue Resolution:

Can you confirm if you basically follow this process?

Copy either QBB or QBW file from old PC to new PC.
Installed and registered QB 2015.
Opened QB and clicked to either restore or open the QBB or QBW file.

If you did (and your old QB password should work), you can try the password reset tool.

http://support.quickbooks.intuit.com/Support/passwordremoval.aspx

Resolution for Issue 'Had QuickBooks pro 2008 and later upgraded to 2012 on my windows XP. XP crashed and I purchased a new PC with windows 8.1. Purchased QuickBooks pro 2015.' available: Yes (Solved).
Source: Intuit Community forum.

Had QuickBooks pro 2008 and later upgraded to 2012 on my windows XP. XP crashed and I purchased a new PC with windows 8.1. Purchased QuickBooks pro 2015.: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

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