"We have lost our developer credentials, so only have the API key. Can someone at Twitter help us get back into the account? Is there a way to contact you directly?
We’re trying to troubleshoot error code 415 , and it seems like the only way to fix this is log in to the dev portal and whitelist the callback_url."
We have the same problem with this case: Lost credentials: How can we get access to Twitter dev portal?.
I tried the suggestion on the answers, created support cases, send a direct message to @TwitterSupport but no help. Seems like I just got automatically reply from Twitter so I came here and hope that some Twitter staff might help me.