[header] How to unlock a phone when you forget its passcode [title] Visit android device manager in a web browser. [step] This method will erase the content from your phone. As of android 5.0, google has removed the ability to bypass the lock code without wiping the content. 
You'll be able to get back into your phone, but you will lose any data (such as music and photos) saved to the device. [substeps] This method will only work if you have android device manager enabled on your phone.