Default Unable to flash because lost root

I had rooted my phone but after some time for clearing up internal memory i did a factory reset.
After that i noticed my wifi stopped working and i had sort of partial root(root explorer worked but titanium backup didn't).
In order to correct that i tried to manually update the su binary by replacing the original with the latest one.Once i did that i lost root completely.
Now i am stuck up with a non root phone without wifi working.
I tried flashing it but that also requires root.
Tried rerooting it with superoneclick(used the same method to root earlier) but it returned access denied
Any help will be appriciated

my phone is spicemi280(stock)