The schematic for the UT58A is available on Elektrotanya.
https://elektrotanya.com/multimeter_ut58a_sch.pdf/download.html#dlI think there are only small differences between the UT58A, B and the UT58C, which you have. I couldn't find a service manual, but having the schematic for systematic fault finding is a lot better than trying to work things out without one.
You didn't say what the abuse was. If it was applying mains voltage while on the resistance range, it could well have caused widespread damage, which may not be obvious.
It's always worth investigating, because often faults are easily fixed, but I suspect you will have to buy a new meter.