I have a Trek Multitrack 7200 hybrid bike with a trashed bash guard. I removed it this morning and just finished a one hour post Thanksgiving meal rest period trying to find a replacement on the Internet. No luck. The crankset is made by Shimano and some of the wording printed on the bash guard include .... Dual SiS Index, Chain pickup ridges, and Special teeth profiles shifting. All of this got me thinking about the necessity of putting a bash guard back on the bike. Other than keeping the bottom of my pant leg out of the chain, what other function does this whimpy plastic part have and should I bother replacing it?
Terry

The plastic "bash guard" you describe is more likely merely intended to keep your trousers out of the chainring than to provide any "bash" protection. If you have some other means to accomplish this end (trouser clip, rubber band, wear shorts, etc.), then no, you don't really have a compelling reason to replace it.

I've dropped my alloy bash guard onto a rock before and it would have been my chainring without it.

What you have isn't a bash guard. Real bash guards replace a big chainring on mountain bikes to protect smaller chainrings from damage from logs and rocks ridden over riding off road

Since you trashed the one that you had, why would you think that you might not need it?

If you are talking a pants guard, those things can be difficult to find in the size and screw pattern needed for a given crankset. Try eBay. Search on "chainring guard".