please .thank you!!!
Have you installed the nRF51 SDK? Can you please try to reinstall and/or repair the installation?
If the SDK has been installed correctly, you should also be able to work around this problem by opening the target options, going on the Device tab, and select the nRF51822_xxAA chip manually, making sure the Generic CPU Data Base is selected.
Edit: I have occasionally seen this error when opening old projects, but it doesn't seem to have any effect. I suspect that the problem stems from the fact that the old device database was removed as part of the upgrade to µVision 5, and the project's reference to it is hence not valid any more. However, if you open the project, and then manually select the nRF51822_xxAA in the Generic CPU database (see attached screenshot), you should not see this error when reopening the project later. This should therefore be a usable workaround.
