The controllers dont hear me. Dont know where the fault is. 2 days ago on 2.6.0 it worked.

There are no changes to this part of the program and other users are not experiencing it.  If you've made any other changes to the PC or are using a new Mic, I would check that first.  Here are some other things to check:

1.    SWITCH SETTINGS: Check to be sure the Power indicator in the bottom left of the main P2A screen is  green.  If not, then you need to turn on the battery switch and avionics switch in the aircraft, or if that doesn’t turn it green, check the 2 options “Ignore Battery Switch” and “Ignore Avionics Switch” in the Config P2A Setup panel.
2.    VALID CALL SIGN: Make sure you are using a valid call sign by changing it to the default Mfg: Beech; Tail Number: N431VB and pressing the Save Button.  You can send me a screenshot of this page and I will let you know if there is a problem with the call sign.
3.    VALID FREQUENCY: Be sure you have a valid frequency showing in the Active frequency display.  Open the Radio Panel and check that the frequency selected has a valid controller assigned.  Try swapping the active and standby frequencies a couple of times.
4.    PTT BUTTON: Use the PTT button on the main screen to eliminate the possibility of it being the Joystick button setup as the issue
5.    VALID PHRASES: Make sure the phrase you are using is appropriate for the controller.  “Say Altimeter” should work with all controllers, so use it.
6.    VOLUME SETTINGS: Check the Windows Volume Mixer and be sure Pilot2ATC volume is turned up. (While P2A is running, rIght click on the speaker icon in the task bar and select Volume Mixer).  Also check the volume of the voices in P2A Config.  On the Communications tab of the Sound dialog, be sure "Do Nothing" is checked for when Windows detects Communications activity.
7.    HEADSET SOUND SETTINGS: If you are using a headset, Windows may recognize that and put a set of "level" settings on the Levels tab of the Headphone Properties.  To set these, select the Headset in the playback devices Windows Settings and press "Properties". Select the Levels tab.  Be sure all levels are turned up as in this screenshot - notice the Microphone setting here on the Playback device:
8.    HEADSET AS DEFAULT PLAYBACK AND RECORDING DEVICE: If you have a headset mic set as the default Recording/Audio Input device, be sure and set the Headset as the Default Playback/Audio Output device.  Some users have had their microphone not working because  they set their Speakers as the Playback device.  
9.    DEFAULT COMMUNICATIONS DEVICE: If using a headset as the default Playback/Recording device, be sure it is not also being used as the Default Communications Device.  This assignment of multiple duties seems to cause a problem.
10.    GRAMMAR HELP SCREEN AND DIAGNOSTICS: Try using the Grammar Help screen.  
⦁    Press the Grmr Help button to the right of the Flight Plan
⦁    Press the Practice button 
⦁    Take a screenshot of the resulting Message box with the connection information and email to me 
⦁    Try saying "Say Altimeter" with no other words.  It should be recognized.  Let me know the result.
⦁    If not being recognized, press the "Replay" button and see what your voice sounds like.  If no sound, then your voice is not getting through to Pilot2ATC.
11.    SOUND DRIVERS AND ADD ON PROGRAMS - Many PCs come with Sound Add On programs from the manufacturer that are run at startup.  Some of these programs may "Capture" the microphone and prevent Pilot2ATC from hearing it.  Also, some addons may have such features.  Check to be sure there are not other sound programs running.  Also be sure that you have the latest Audio Drivers for your Microphone installed.
 

This was resolved by deactivating all audio inputs except the desired mic and then setting the mic as the default audio input device.  A Windows update had apparently modified the Windows audio settings.