AdWords API expert needed

Need someone who is good in AdWords APIs to fix a simple issue. I'm having troubles with getting an authToken with the following error message: **Failed to get authToken. Reason: BadAuthentication** Need to fix that and also make the code get a monthly keyword search value for specific domain name. I have everything almost set, it is only few lines of code with a simple fix for someone who is good in AdWords APIs Thank you in advance.