From a fundamental perspective, the present value of a bond depends on prevailing interest rates, future cash flows (coupon + principal at maturity), and the probability of said cash flows being made on time.
All else equal, if investors have reason to believe that a borrower will miss one (or many) payments, the value of the bond will decrease but it will rarely plummet to zero.
By how much? What you're really asking is what recovery rate can be expected, to borrow a term from the CDS (Credit Default Swap) market.
It depends on the type and severity of the credit event. A single missed payment due to temporary liquidity issues at an otherwise sound corporation would have less of an impact than a string of bankruptcies in a declining industry, for example.
For a single bond, it makes sense to do your due diligence by reading the bond prospectus, checking the credit rating, looking at the balance sheet, thinking about the economic outlook, etc. on a case-by-case basis.
Alternatively, you could invest in an ETF (Exchange Trade Fund) or Mutual Fund that fits your objective to benefit from diversification.