You can get it absolutely free and in very short time. We Flash our mobiles at those stages if phone is working slowly or completely break with due to its expired or corrupted firmware.
Their are several flashing tools or boxes which helps you in flashing . Please take a back up of your data before flashing.
Otherwise you will lose your important data. You can restore it after successful flashing. Now you can download latest Stock ROM of HTC Explorer from below download buttons.
Guy's it is absolutely free and scanned by all types of viruses. You can download without any problem below sharing link here,
Start download links
HTC Explorer A310E Firmware Download