Hi mladha,
Welcome to the Apple Support Communities!
Being able to text from Messages on your Mac is a great feature and I can understand wanting the functionality if it is no longer working. To troubleshoot this situation, I would recommend reading over the steps in the attached article to ensure that the service is set up correctly. Please let me know if it is and you are still unable to send regular text messages.
Connect your iPhone, iPad, iPod touch, and Mac using Continuity - Apple Support
- Your iPhone, iPad, and iPod touch need to use iOS 8.1, and your Mac needs to use OS X Yosemite.
- Sign in to iMessage on your iPhone, your other iOS devices, and your Mac using the same Apple ID.
- On your iPhone:
- Go to Settings > Messages > Send & Receive > You Can Be Reached By, and add a check to both your phone number and email address.
- Go to Messages > Text Message Forwarding, and enable the device(s) you would like to forward messages to.
- Your Mac, iPad, or iPod touch will display a code. Enter this code on your iPhone to verify the SMS feature.
Best regards,
Joe