Hello Friend,
Read about your issue that you are facing problem using POST request, and as you have mention it is suddenly stopped working, so i would like to know in,
1) which android versions you have tested before? Are you testing in the same version of the android? If not then in which version of android are you testing your application?
2) Are you using HttpClient or HttpUrlConection class for post request?
3) Are you using any third party library for network operation?
Thank you for your time to read about my proposal and question, looking forward to help you resolved your issue.
Thanks,
Silvans