No se está detectando mi disco duro

dmesg muestra:

[  115.732614] Non-volatile memory driver v1.3
[  167.790324] ata6: exception Emask 0x10 SAct 0x0 SErr 0x4050000 action 0xe frozen
[  167.790328] ata6: irq_stat 0x00000040, connection status changed
[  167.790329] ata6: SError: { PHYRdyChg CommWake DevExch }
[  167.790333] ata6: hard resetting link
[  173.530844] ata6: link is slow to respond, please be patient (ready=0)
[  177.797005] ata6: COMRESET failed (errno=-16)
[  177.797015] ata6: hard resetting link
[  183.567872] ata6: link is slow to respond, please be patient (ready=0)
[  187.850000] ata6: COMRESET failed (errno=-16)
[  187.850005] ata6: hard resetting link
[  193.620842] ata6: link is slow to respond, please be patient (ready=0)
[  222.871503] ata6: COMRESET failed (errno=-16)
[  222.871514] ata6: limiting SATA link speed to 1.5 Gbps
[  222.871516] ata6: hard resetting link
[  227.913991] ata6: COMRESET failed (errno=-16)
[  227.914000] ata6: reset failed, giving up
[  227.914007] ata6: EH complete

Mi unidad de disco duro es la unidad portátil Toshiba 500gb.
uname -a salida:

Linux mubashshir-mint 4.10.0-42-generic #46~16.04.1-Ubuntu SMP Mon Dec 4 15:57:59 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

¿qué hacer?