The Sharp LC-32SB24U has menu, input, volume up/down and channel up/down buttons on the top of the TV. When you access the Menu using the buttons on the TV, the Input button is the same as the Enter key. The volume up/down buttons map to the left and right arrows. The channel up/down buttons remain up and down. The Menu button is the closest to the power button (on the right). The volume buttons are the ones on the left.
Make sure that the input is set to TV to change channels. Then you need to program the available channels, access the Menu and navigate to Setup (left/right arrows). Press Input to enter this sub-menu. Then use the Up/Down arrows to select CH Setup. Press Input again to enter. Now you can set the channel source and let the TV scan for channels that have a strong enough OTA signal or are unencrypted cable channels. These are the top two options in the Channel Setup menu. The details are available in the manual which is available here: http://static.highspeedbackbone.net/pdf/Sharp_LC37SB24U_LC32SB24U_Manual.pdf
. For OTA channels, you may need to check the signal strength under the Antenna Setup - Digital option in this Setup menu. OTA Digital signals will not be tuned in if the signal strength is low. It's an all-or-none tuning; amplifiers and external antennas may help. See tvfool.com for details of transmitters and the recommended antenna for your area. (Warning: damaged amplifiers can become filters and block the signal on some channels. Replace the amplifier if it is damaged.)
If you look to replace your original remote with a universal remote, you'll need one that was programmed more than 6 months after the TV was released. That may be 12/2005 based on the manual copyright date. Look for a remote that has a Menu and Input or Source button and check all of the codes to find one that matches all of the features on your original remote. Amazon has an OEM remote for the LC-32SB24U; remotes.com also has a replacement remote available that has been programmed for the TV. (On remotes.com, search for the LC32SB24U.)
I hope this helps.