Can't open config.txt with nano error reading. - Raspberry Pi Forums

i tried overclocking pi. got far edit config.txt on laptop's card reader

after getting 1300 worked! can't open config.txt anymore gives me

error reading lock file /boot/.config.txt.swap: not enough data read

weird thing oc first made fast (1340) lowered safe. slower, returned stock now. it's still slower. restarted , ran again , it's fast again. it's sysbench giving me random results!
tried overvoltage=6 , didn't hot. had remove plug because froze

anyway. how can fix problem now?

edit: ok disk bench down 14mb/s 23.3mb/s wth have done? have done ( have damaged pi/sdcard ???

don't overclock pi.
why overclocking? have heatsink and/or fan?

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