Will not recognize a tape. new or pre recorded

The vu meters only show that there is an input signal. The meters do not mean the deck is actually recording. If the deck will play a previously-recorded tape, how well does it sound? if the sound quality is muffled or very low, the play-back heads are dirty. If the playback heads are dirty, then the erase and record heads are too. In the tape path, the direction your tape moves from supply reel to takeup reel determines which heads are in which order. Most R-to-R decks play from left reel to right reel. The magnetic heads are in this order, with the the arrow indicating tape transport direction:
Supply Reel moves tape across > Erase head first, then across > Record head second, then across > Playback head. Some machines use the same head for record and playback, but no machine uses the erase head for anything but erasing pre-recorded material on the tape.
First, using tape recorder head cleaner or rubbing alcohol, clean the erase head (the first one the tape moves across) thoroughly with a Q-tip. If the heads are VERY dirty, use a pencil eraser AND the Q-tip. If this head is not clean, it will either not completely or not at all erase the material already on the tape. If the tape isn't erased, you either will get your new recording laid over the top of the existing one and it will sound like gibberish, or the new recording will not be recorded at all, and the original recording is all you will hear. Next, clean the second head the tape passes over. Usually this is the record head. If it is dirty, it will not record clearly or at all the material you are trying to record. Last, if there is a third head (most decks have this), clean it thoroughly as well. This is the playback head, and if it is dirty enough, you will hear nothing, although your new recording may very well have been laid down on the tape. Always clean all tape heads at the same time; in other words, don't just clean one head and not the rest of them. Clean all tape deck heads AS WELL AS the capstan (skinny metal pin that rotates) and pinch roller (the rubber wheel that 'pinches' the tape between itself and the rotating metal pin) thoroughly, rethread your tape through the head array, capstan, and pinch roller onto the takeup reel, and see what happens. If everything is clean and you still don't get any playback of your recording but you do get playback of pre-recorded tapes, then the problem is in the record circuit, and can be anything from faulty input stages to a bad head--deck heads DO go bad, although not often. If this is what happens, you have to take the unit in for repair by a qualified technician.

Are these all commercial pre-recorded tapes? Or are they tapes that were recorded at home? Is the tape deck one that the tape loads in from the short side and must be flipped around to play the other side....or is it one that the tape loads in with the tape facing in and is auto-reversing? Pre-recorded commercial tapes should work on most machines without problems. Home recorded tapes can be a problem, especially on the type of deck that the tape must be swapped over to play the reverse side. Many users use C90 or C120 tapes to home record. These tapes are thinner than normal tapes and are prone to getting overly tight and then can break and/or stretch. This causes jamming in the deck and distortion of the playback.

I have the same problem. I just bought a sony handyman and tried to play my old tapes and nothing, not even sound. But I just recorded something using an old tape and it records and I can play that back. I'm thinking maybe over time, somehow all the data on there got erased. Which is really a bummer.

The playback head is dirty. Insert a brand new tape into the drive and perform a record, through the entire tape until it reaches the end. Then play a pre-recorded tape.

The head is dirty or bad - insert a brand new blank tape in the camcorder and perform a record through the entire tape without stopping the process until it finishes the record all the way through - this should clean the heads. Playback a pre-recorded tape. If it plays back ok then attempt an actual record. If unsuccessful, then the heads are bad.

Make sure the tape you are trying to record to is not restricted (unrecordable or pre-recorded). You can look at the tabs on the top narrow band and if they are punched out the tape will not accept recorded material. (you can put scotch tape over the hole and still record but only if you are desparate!)

Trace the wires from the head to the amp section. Put your finger on where they join (during playback) and see if you can get a buzz. If you can't on either channel, look for something that might be common to both channels. Either a switch, or a pre-amp IC, as being the cause of the fault.

A good cleaning to the rollers and tape head with a qtip and a small amount of rubbing alcohol should do the trick

It seems to be fixed. I ran a new tape through the machne as suggested. To be sure, I also used a VHS head cleaning cassette.Works fine, now. Thanks

If it plays back pre recorded tapes then there is nothing wrong with that section of the unit. Does it playback audio and not picture or does it not playback anything.
Also, when trying to playback a recording what is seen of the screen? Snow(black and white dots or wiggly picture?

The unit uses two separate circuits to record and playback tapes. Is any thing else connected to the unit while you are recording? If you are using anything plugged into other ports on the recorder it may not see the camera input causing it to not record anything..