Soil borne tomato diseases

My tomatoes died off in early august this year might be nitrogen or a fungul disease and i can't determine what it is. Should i just replace the soil in my raised bed and clean my tools?

It could be a few things. The obvious one is if you've  planted tomatoes in the same bed for a number of years.

If they've been planted in the same bed, then you may have nematodes. The normal non-toxic treatment, is to plant marigolds and mustard plants in it, let them mature until they're sappy, then dig them in - natural fumigant.

Otherwise, it may be inconsistent watering, wetting the foliage, fertilising at the wrong times, etc.

Need more info before it can be narrowed down.