I got the scale of the airplane wrong in my post (I gave fair warning about my memory.) Your model is a 1/72 Revell B-25B/C, which is a reboxing of the Italeri kit. (Italeri is an Italian company, some of whose kits have been reissued under the Revell label.)
Unfortunately that kit is out of production. (I checked the Italeri website.) Italeri does produce a B-25G, which looks quite a bit different - but the propellers probably would fit yours. I haven't found one for sale on the retail hobby shops I normally check, but there may be one out there. If there is, it probably would be pretty expensive.
The most economical alternative might be the Airfix B-25H kit. It doesn't have parts for a B-25B (which is what the Doolittle Raiders flew), but parts like the propellers should be pretty close. Here's a link: http://www.airfix.com/us-en/north-american-b-25h-mitchell-gift-set-1-72.html . At $25 it's not cheap, but I don't know of a cheaper alternative.
The Revell Hornet is out of production.
You might - just might - be able to get Revell to send you replacement parts for the B-25 and decals for the Hornet. But frankly I doubt it. Both those kits have been absent from the Revell catalog for a long time. Anyway, the Revell website is www.revell.com . There's a parts replacement request form on that site: http://www.revell.com/support/index.html . But note that the company only stocks parts for kits that have been in production during the last three years. I'm pretty sure yours hasn't.
Hope something in this post helps, though. Good luck.
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