I lost 156,000 in a business where i had 20% ownership. There was no sale, the business folded. how can i enter a capital loss for this amount when there was no sale?

this may be an ordinary business loss. however, the business probably has to file a return so the loss can flow through to your personal return.     a capital loss can only be used to offset capital gains any excess is only deductible up to $3,000 per year whereas an ordinary loss is fully deductible in the year incurred.  perhaps you were in a scam.  it may be best for you to contact a tax pro in your area who can go over the situation with you and provide proper advice. 

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The first thing we would need to understand is what type of business entity you had ownership in.  

The responses have assumed that this is some type of pass-through entity, which it may be, but we don't know yet.  This could be a C corporation, in which case, you will not get any type of K-1.