@Kevin_Z @All thanks for your reply i made hard reset for around 13 seconds then it works Although I did before but for 10 seconds but didn't do it now it's ok

@Kevin_Z thanks Kevin for you feedback for the router leds, i have power - DSL - WiFi leds always on, internet led off. i tried the solution below as was suggested with ISP during troubleshooting....

HI The router was fins all the time for more than a year, then once the internet led is off - DSL led is on. but no internet on devices connected. revised with ISP , troubleshooting all ways still...