NO Dial tone when connecting to INternet

I Had been connecting fine to the internet and then after 1 week i got a message saying couldn’t connect no dial tone then i took modem out put it back and it worked fine i didn’t get that message for another 3 weeks i then replace the 12 ft phone line with 2 6 ft lines connected by a coupler and then i got the message after 5 days was wondering if i needed a new modem or try a brand new phone line thanks for any help you can give me