I have to resetup all of my tv and cable channels

If reset does not do the trick, then you may have an issue with the board (main) that has the electronics for programming on it.

If you're referring to your xfinity tv receiver (the cable box) there's a few different ways. Please keep in mind without much information, it's difficult to give a 100% direct answer.

There are four ways to connect it. We'll start with what will give you the best video quality, going to the worst.

HDMI cable: A single cable with a flat end. Your TV and receiver will have port labeled "HDMI". You plug it in, and then use your tv remote to set it to the HDMI channel. You may have source or input button on the remote. Press that, and a list of options will appear on your tv. Select HDMI. If there is more than one HDMI (as in HDMI1, HDMI2) try each one until you get a picture.

Component cable: A cable with 5 ends. They're color coded, so match up the colors. Then try that input our source button to select the COMPONENT option on your tv.

RCA cable: A cable with three ends. Color coded. Follow the same directions as above in regards to the correct "channel" to put it on.

Coax: A single cable, an end that screws in. Its connector will look like something can be screwed on it, with a hole in the middle for the pin to go into. Connect it, then tune your tv to channel 3 or 4.

I would try two things here---first with the remote for the set direct enter with the numbers on the remote 02 and enter to see if set will go there and second connect a different set to that connection to see if same issue or not.

You can download the manual from

http://www.retrevo.com/d/ds/progress?doc=d74782ab23218f4c972a807a9afa3fc7&rk=0.15356064987977386

To manually program your unit,
1. Manually turn on the device (TV, VCR, etc.) to be
controlled.
2. Press and hold the SETUP button until the red
indicator stays on, then release the SETUP button.
3. Press and quickly release the desired mode button
(TV, VCR, etc.). The red indicator blinks off once.
4. Press the CHANNEL UP button repeatedly (up to
300 times) until the device to be controlled changes
channel. The red indicator blinks off with each
button press. If you accidentally overshoot the
code required, press the CHANNEL DOWN button
to backtrack through the library until the device
changes channel. Pressing CHANNEL UP changes
direction to forward again.
5. Press and release MUTE to install the code.
Most users will store VCR codes under the VCR button,
Cable codes under CABLE, etc. If (for example) you
want to store a VCR code under CABLE, first follow the
procedure for Direct Code Entry (previous page) and
press CABLE in step 2 of Direct Code Entry, then enter
ANY VCR code in step 3 of Direct Code Entry. Then
follow the steps above for Code Search (or Brand
Search, below). Note: If the device does not have a
CHANNEL UP button, use PLAY (VCR only) or
POWER instead. Code Search starts from the currently
stored 4 digit number under that mode.

I'm not positive but these codes should work, if not try the CODE SEARCH function. I'll post the Code Search instructions first, then I'll post the Brand Codes (list is a bit long so it might take a couple of posts). Let me know if any of this helps you and I'll continue to search for a pdf type of code list for the mru3300 for you.
*CODE SEARCH
If your product does not respond after you have tried all
the codes for your brand, or if your brand is not listed,
try searching for your code by following these steps.
1. Manually turn on the device (TV, VCR, etc.) to be
controlled.
2. Press and hold the CODE SEARCH button until the
red indicator stays on, then release the CODE
SEARCH button.
3. Press and quickly release the desired mode button
(TV, VCR, etc.). The red indicator blinks off once.
4. Press the CHANNEL UP button repeatedly (up to
300 times) until the device to be controlled changes
channel. The red indicator blinks off with each
button press. If you accidentally overshoot the
code required, press the CHANNEL DOWN button
to backtrack through the library until the device
changes channel. Pressing CHANNEL UP changes
direction to forward again.
5. Press and release MUTE to install the code.
Most users will store VCR codes under the VCR button,
Cable codes under CABLE, etc. If (for example) you
want to store a VCR code under CABLE, first follow the
procedure for Direct Code Entry (previous page) and
press CABLE in step 2 of Direct Code Entry, then enter
ANY VCR code in step 3 of Direct Code Entry. Then
follow the steps above for Code Search (or Brand
Search, below). Note: If the device does not have a
CHANNEL UP button, use PLAY (VCR only) or
POWER instead. Code Search starts from the currently
stored 4 digit number under that mode.

If your product does not respond after you have tried all
the codes for your brand, or if your brand is not listed,
try searching for your code by following these steps.
1. Manually turn on the device (TV, VCR, etc.) to be
controlled.
2. Press and hold the CODE SEARCH button until the
red indicator stays on, then release the CODE
SEARCH button.
3. Press and quickly release the desired mode button
(TV, VCR, etc.). The red indicator blinks off once.
4. Press the CHANNEL UP button repeatedly (up to
300 times) until the device to be controlled changes
channel. The red indicator blinks off with each
button press. If you accidentally overshoot the
code required, press the CHANNEL DOWN button
to backtrack through the library until the device
changes channel. Pressing CHANNEL UP changes
direction to forward again.
5. Press and release MUTE to install the code.
Most users will store VCR codes under the VCR button,
Cable codes under CABLE, etc. If (for example) you
want to store a VCR code under CABLE, first follow the
procedure for Direct Code Entry (previous page) and
press CABLE in step 2 of Direct Code Entry, then enter
ANY VCR code in step 3 of Direct Code Entry. Then
follow the steps above for Code Search (or Brand
Search, below). Note: If the device does not have a
CHANNEL UP button, use PLAY (VCR only) or
POWER instead. Code Search starts from the currently
stored three digit number under that mode. Good Luck.

try entering the channel directly via the remote by pressin"03" if that fails check to see if your cable box has a 3/4 switch on the back. if so set it to 4.
The main problem however, is that the TV needs to have the channels reprogrammed by following the instruction manual and/or on screen menu.

Use the TV input selector to select the right channel, that should fix it.

The problem is not with your TV. You need a digital box to unscramble the channels.

I think the low band (Channel 2-6)in your tuner is not working. This could be in the tuner itself or in the band switching circuits. Possibly she deleted the low channels or locked them out. Stargazer