I could not find the manual for your TV, but I did find one for model number 27N-S50 so hopefully they're very similar. If you DVD/VCR is connected to your TV with composite cables (the RED, WHITE, YELLOW cable set) then you need to change the input mode. There should be a button labeled Input on your remote and pressing it will cycle between the various inputs (Cable, Input1, Input2). I would guess your DVD/VCR is connected to Input 1. If you have lost the remote you should be able to get to the other inputs by using the channel selector button. Tune the TV to either the highest or lowest channel in memory and then press either the CH UP or CH DOWN button on the TV to cycle through the various inputs.
The other thing you should know is that there is a recall on this TV related to the power button. I discovered this while looking for the manual on the Sharp website. Go to this website:
Type 27R-S50 in the model box and select Television/Home Theater Projectors in the Product box then click on Get Results and you'll get information on the recall.
Also, if the info I've given about how to select the input does not work, there are links on the above site to help you get the correct manual.
Lastly, I don't get paid for this. I know it's a strange hobby, but I like to help out when I can. I hope you'll take a moment and give a prositive rating if this information has been helpful to you. Nearly half of the solutions I've posted have never been rated. Thanks and good luck.