Htc one m7 software problem ***software status: modified*** locked *** security warning***

[AC Question]

So i had this phone for 1 and a half years and when i traveled to europe and replaced the sim card.. the phone stopped working...even if it was neverlocked ! Now all that i can see on the hidden menu ( power plus volume down) is :

*** software status: modified ***
***LOCKED***
***SECURITY WARNING ***

M8_UL PVT SHIP S-ON
HBOOT-3.19.0.0000
RADIO-1.29.214500021.12G
OpenDSP-v51.2.2-00593-M8974_FO.1015
OS-6.12.401.4
eMMC-boot 2048mb
Dec 17 2015, 14:15:48.13015

I only have this following options

Hboot
Fastboot
Recovery
Factory reset
Simlock
Check smartsd
Image crc
Show barcode

And if i go in fastboot

Hboot
Ramdump
Reboot
Reboot fastboot
Power down

If i press reboot the phone will restart and will work but i won't have the 3 buttons to navigate in the phone available on the down side of the screen , i won't be able to go back in previous menu if i sekect a option.
Please help and please explain the solution step by step because I'm new in all this.. thanks.