I can't send message for Friends

@belayzeleke you are not giving us a lot to work with here. It would be nice to know if this just started all of a sudden or if this started after an update etc. Also, does everything else work the way it should or does your phone have other issues as well. For now I suggest you try a force restart to reset your phone. You do that by

• Press and hold the volume down button and the power key key simultaneously for 10 seconds or until the phone reboots.

See is that did anything.

IF that did not do anything then you want to try to text in safe mode. Safe mode disables all third party Apps that may be the cause for this.

• Turn your phone off.
• Press and hold the Power key past the model name screen appearing on the screen.
• When SAMSUNG appears on the screen, release the Power key.
• Immediately after releasing the Power key, press and hold the Volume down key.
• Continue to hold the Volume down key until the device finishes restarting.
• When Safe mode appears in the bottom left corner of the screen, release the Volume down key.

Now send a text to yourself so you know you are receiving it. If so, then you know that this is a third part App that is causing the Texting not to work.

If it does not, then it is possible that this is a network settings issue. You may have to reset those.

1. From the Home screen, swipe up on an empty spot to open the Apps tray.
2. Tap Settings > General Management > Reset > Reset network settings.
3. Tap RESET SETTINGS.
4. If you have set up a PIN, enter it.
5. Tap RESET SETTINGS. Once complete, a confirmation window will appear.

For more on this, check the Samsung site