Can't be answered without knowing what model.
value depends on overall condition
100-400 USD
Impossible to value without a detailed description of all markings and features.
No, no, no. Do not attempt to do this.
0-300 USD depending on condition, box, papers, accessories, etc..
Mint NIB 650 Used 9/10 575
50-500 usd
You can request a owner's manual for free at the SMITH AND WESSON web site.
If you go to You-Tube and type in disassemble of Smith and Wesson model 915;there should be a video of the steps needed to take down your smith and Wesson semi-auto 9mm.
100-400 USD
50-400 usd
100-450 or so