I accidentally deleted my '' bin '' folder and also my .config. My router has been flashed with my latest .config and everything is ok but I would like to know if from my image on the router and / or with my working folder / openwrt / folder, if it is possible to recreate my .config?
No.
/etc/config is only for uci config files for router itself.
It would be a file called /etc/build.config
(and it contains only the deviations from defaults, not the full .config, which would be much larger. You can expand that to .config by first copying it to be .config and then run make defconfig )
112 config INCLUDE_CONFIG
113 bool "Include build configuration in firmware" if DEVEL
114 default n
115 help
116 If enabled, buildinfo files will be stored in /etc/build.* of firmware.
A bit cryptic that it requires extra options from another menu to be visible.