How to get unit to play without remote
You can probably use the front panel buttons (STOP PLAY OPEN/CLOSE etc) manually, the only thing you cannot do without the remote is access certain DVD menus, including subtitles/language/special features etc. You can always obtain and use a universal remote for basic menu functions later on if necessary.
To play a DVD movie without the remote, simply load your preferred disc, wait for the player to finish reading its contents, then to skip copyright warnings and/or the 'play movie' menu screen, press STOP, then PLAY, or simply press PLAY button where 'play movie' (or whatever function) is highlighted in the menu. These buttons should be on the front of the main unit. Doing this should encourage the player to detect the appropriate title (the movie) and play it (basic playback operation may not be possible with some DVD releases due to the numerous interactive menus and title pages, such as film trailers).
If basic manual operation is not completely possible with some DVD titles, consider a universal remote for your player if you have either lost your original, or the player was purchased/received without one. Such remotes are relatively inexpensive to purchase, and are available just about everywhere.