Hello Bigdaddy39. I regret to hear of the trouble you're having with your iPhone 6 plus. That's a great phone you have. Which third party app did you attempt to access? Are you having trouble with anything else, calls or texts? Share further details. Thanks.
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3rd party as in, not from Apple App Store because you jailbroke the Phone? If so reset and setup again with iTunes
IF not, reboot your phone by holding the power and home button until your phone turns off, then on again, then release the buttons. This will not effect your data.
delete the problem application.