My honda won't drive forward, only drive in reverse and what are the possible problems and how much wil it cost

More then likely you are experiencing a transmission problem, an internal problem that may need to be repaired by either having your transmission rebuilt by a reputable transmission overhaul shop or replaced by a transmission that has already been rebuilt and in stock for your vehicle.
Indications of this type of problems are, burnt transmission fluid a burnt smell as well as a burnt coloration of the fliud(not bright red like it is in the can) and a least likely problem that may require the transmission being serviced by means of a transmission fluid service change and believe it or not a transmission filter replacement, at times these filters clog with dirty fluid and debri from the transmission clutches,etc, and create a no go condition in the hydraulic workings of an automatic transmission.
Replacement transmission costs can be as high as $1500.00/rebuilding of your transmision depending on what "hard" parts need to be replaced can start at $800.00 and go upwards of $1500.00.
A transmission service can be the least expensive of the evils starting from $49.95 to upwards of $100.00 if the shop flushes the transmission by means of a hi-tech flush machine attachment.