I have a master lock model m175 that is locked and sitting on my desk and I don't know the combination can you help?

Google

make model manual
or
make model change combination

It is impossible for us to guess what you have. Here are a few just for fun!

"Set-Your-Own" Combination Locks Instructions ' FAQs

https://www.masterlock.eu > ... > FAQs > Padlocks

Q: How do I set or reset the combination on my bike cable lock model 8221, 8231, 8120, 8190, 8226?

Change my combination? - S&G - Sargent & Greenleaf

https://sargentandgreenleaf.com > knowledgebase > kno...

Do not remove lock cover. If an error is made, re-dial the entire combination. A U8 change key is required to change the combination. If you ...

Support FAQs ' Master Lock

https://www.masterlock.com > Support

Q: How do I set or reset a Master Lock combination padlock that has a ... Q: How do I change the combination on a Set-Your-Own combination lock model #643D?

How do I set or reset the combination on my Lock Box?

https://www.snapsafe.com > support > faqs > how-do-i-...

Begin by opening your Combination Lock Box. To open a new lock box for the first time: Move all 3 digits to 0-0-0. Make sure all digits are centered on the ...

To change the combination on a Set-Your-Own combination lock model 646D, 647D, or 646T, follow these steps:

• With dials at 0-0-0, pull out shackle.
• Turn shackle counterclockwise 90° (1/4 turn) and press it down.
• Continue pressing shackle and turn another 90° (1/4 turn).
• Set the dials to your own combination.
• Turn shackle clockwise back to the original 90° position. Lift and return shackle to closed position.

Help with Forgotten or Lost Lock Combinations from Master Lock Master... The locksmiths will not give combination without you visiting a dealer. Maybe you can at first try a few different combinations to see if you can do it yourself but don't get frustrated and take the lock to a dealer to save time and energy.

If this is an older masterlock with a serial number, you can fill out the form located here http://www.masterlock.com/pdfs/lost_combo_form.pdf
Read the below from masterlocks website: Due to increased security concerns nationwide, Master Lock recognizes the heightened need for additional safety measures. We no longer provide lock combinations in response to phone, fax, or email requests. Please follow the procedure outlined below to obtain the combination to your lock and submit your request to:
Master Lock Warehouse
1600 W. La Quinta Rd
Suite/WHSE # 1
Nogales, AZ 85621Procedure:

• Print out the Lost Combination Form from a printer friendly page, or download the PDF file.
• Have your Lost Combination Form notarized by a Notary Public to prove that you are the owner of the lock (you can include up to 6 combinations on one notarized form).
  
  • Note: Inmates at a correctional facility - in addition to the lost combination form, you must submit your request on official prison letterhead. In lieu of notarization, the form must be signed by a prison official.
• Photocopy the serial number on the back case of your combination lock. This copy MUST clearly show that the lock is not attached to anything. Be sure to hand write the serial number on the photocopy.
• Mail the original completed, notarized Lost Combination Form and the photocopy of the back of your lock to the address above.

Note: It will take approximately 4 to 6 weeks to process your request for a combination.

Note: If the form is not fully completed and notarized with a raised seal or rubber stamped seal, or if the serial number is not legible on the photocopy, your request will not be honored. Master Lock does not reimburse for any Notary fees.

Open the lock and take the end cap off (on the side that doesn't say "Master") and then the wheels. Make sure the red markers are aligned with the word "Master," then slide the wheels you want to use back on, spelling out your combination in alignment with the red markers. Slide the end cap back on and close the lock. Your combination will be set.
Note: if there are no red markers, there should still be metal protruding a bit where the markers should be. It will look a bit like the metal has been embossed.
To watch an instructional video of this, click on the YouTube link.

Sorry, I don't think there is a remedy, but you could try removing it, and reinstall again.

Bolt cutters or a lock smith

your answer is on this site
http://www.masterlock.com/faq/lostcombo.shtml

open the shackle twist 180 degrees...shut it as if u were closing it into the locking device..hold it down, put in what ur new combination is..pull the shackle up and shut it into locking device, and test it out.

Have 5400D Master Lock. Know combination, but it will not open. Can someone help me?