Suggest you contact the benefits administrator or the H/R department for your current or previous employer or call the custodian directly. Generally speaking, distributions from a 401(k) is taxable income and is subject to an early withdrawal penalty if you are under age 55.
You will not be able to withdraw funds from you 401(k) if you are still employed by the company who is providing the plan. There are some exceptions such as hardship or first-time home buyers. Some plans allow loans.
Warmest regards John Essigman www.bluecreek.net
To add to John's answer:
The IRS will slap you with a 10 percent penalty if you withdraw money from your 401(k) before reaching 59 1/2, unless you can prove a financial hardship. This is on top of regular income taxes on the withdrawal. The 10 percent penalty disappears after 59 1/2, but you are still liable for the income taxes.
As always, please consult with a local advisor before you withdraw funds from your retirement plan and hurt your long term retirement goals. Your HR department should be able to direct you in the direction you want to go and what the plan offers to it's participants.