Changing the term of your mortgage can help in several ways. First, if you were to refinance your current mortgage from 30 years to 15 years, you will accelerate the rate at which you pay towards principle each month meaning your house will be paid off quicker. Also, you will save an unbelievable amount of money in terms of interest because you would likely be taking 10 to 15 years off the life of your loan. Second, you can also refinance a 15 year mortgage to a 30 year mortgage. It seems like it might not make sense to do this, but if you have an immediate need to free up monthly cash-flow and you don't want to take out a home equity loan, this can work out to your benefit. When you take a 15 year loan and refinance it to 30 years you will have the same balance only the payments can be hundreds of dollars less than the 15 year loan. The only draw back to this is you will pay more in interest over the live of the loan.
Refinancing a mortgage means the owners are paying off their existing mortgage and replacing that mortgage with a new loan. Generally, the costs associated with mortgage refinancing are rolled into the loan, meaning they are added to the existing balance, increasing the loan amount.
Homeowners who want to refinance but can't because they owe more on their home than their home is worth (also known as "upside down") should focus their time and energy on making more money. Adding a part-time job or starting a side business will bring extra income into the household, income that can be used to make extra payments a mortgage.
If you have bad credit, find a lender who is willing to work with you and offer you reasonable loan terms.