Is it possible to start back over fresh?
Sure is. This unroots your phone, so you will need to re-root afterward.
[ROM][10/20/2010]FlashBack21 v1 -Return to Factory Stock - UPDATED - xda-developers
Before you do that, though, you might want to do the following: open up a web page. (say Google, for instance), and
long press the text entry box. Select "Input Method" and select your default keyboard.
It is somewhat unusual for the installation of an alternate keyboard to destroy the default keyboard. If you've installed a keyboard which crashes every time you tried to use it, the solution is usually to revert to the default keyboard using the "Input Method" selector.
eu1
PS I'm not sure that keyboard you downloaded was ever intended for the Eris; I only found references to it on the web in the the context of the Nexus 1. The installer writes a shared library into /system/lib, and that is definitely non-standard behavior, compared to normal ".apk" packages. (That sort of behavior is not very portable between different phone models, depending on what the library does)
If you want an alternate keyboard that looks like the original HTC 1.5 keyboard, and includes a voice search key, I have had good luck with the "Low Resolution" v22 keyboard (/htc_ime_jonasl_lowres_22) on every ROM I have tried it on (Android 2.1/2.2). I may have tried v27 a long time ago, but can't remember what my experience was with it. I know that lowres v22 works, though, on all the Eris dev ROMs... and am sure that there are even better keyboards available for a little scratch on the Market.
[ Edit ] Whoops! That keyboard can be found here:
[MOD] HTC_IME (8th June) v27: Small fix - xda-developers